…part 1 (elastic#211300)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, in this PR we're consistently:

- Changing the file names and test plan titles.
- Adding or expanding test plan summaries.
- Regenerating tables of contents using the [Markdown All in
One](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)
VS Code extension.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

(cherry picked from commit 9600de4)

…part 1 (elastic#211300)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, in this PR we're consistently:

- Changing the file names and test plan titles.
- Adding or expanding test plan summaries.
- Regenerating tables of contents using the [Markdown All in
One](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)
VS Code extension.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

(cherry picked from commit 9600de4)

…part 1 (elastic#211300)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, in this PR we're consistently:

- Changing the file names and test plan titles.
- Adding or expanding test plan summaries.
- Regenerating tables of contents using the [Markdown All in
One](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)
VS Code extension.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

(cherry picked from commit 9600de4)

…lans, part 1 (#211300) (#211307)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Security Solution] Refactor prebuilt rule customization test plans,
part 1 (#211300)](#211300)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Georgii
Gorbachev","email":"georgii.gorbachev@elastic.co"},"sourceCommit":{"committedDate":"2025-02-14T18:22:45Z","message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","test-plan","v9.0.0","Team:Detections
and Resp","Team: SecuritySolution","Team:Detection Rule
Management","Feature:Prebuilt Detection
Rules","backport:version","v8.18.0","v9.1.0","v8.19.0"],"title":"[Security
Solution] Refactor prebuilt rule customization test plans, part
1","number":211300,"url":"https://github.com/elastic/kibana/pull/211300","mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},"sourceBranch":"main","suggestedTargetBranches":["9.0","8.18","8.x"],"targetPullRequestStates":[{"branch":"9.0","label":"v9.0.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"8.18","label":"v8.18.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/211300","number":211300,"mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Georgii Gorbachev <georgii.gorbachev@elastic.co>

…lans, part 1 (#211300) (#211308)

# Backport

This will backport the following commits from `main` to `9.0`:
- [[Security Solution] Refactor prebuilt rule customization test plans,
part 1 (#211300)](#211300)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Georgii
Gorbachev","email":"georgii.gorbachev@elastic.co"},"sourceCommit":{"committedDate":"2025-02-14T18:22:45Z","message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","test-plan","v9.0.0","Team:Detections
and Resp","Team: SecuritySolution","Team:Detection Rule
Management","Feature:Prebuilt Detection
Rules","backport:version","v8.18.0","v9.1.0","v8.19.0"],"title":"[Security
Solution] Refactor prebuilt rule customization test plans, part
1","number":211300,"url":"https://github.com/elastic/kibana/pull/211300","mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},"sourceBranch":"main","suggestedTargetBranches":["9.0","8.18","8.x"],"targetPullRequestStates":[{"branch":"9.0","label":"v9.0.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"8.18","label":"v8.18.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/211300","number":211300,"mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Georgii Gorbachev <georgii.gorbachev@elastic.co>

…plans, part 1 (#211300) (#211306)

# Backport

This will backport the following commits from `main` to `8.18`:
- [[Security Solution] Refactor prebuilt rule customization test plans,
part 1 (#211300)](#211300)

<!--- Backport version: 9.4.3 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sqren/backport)

<!--BACKPORT [{"author":{"name":"Georgii
Gorbachev","email":"georgii.gorbachev@elastic.co"},"sourceCommit":{"committedDate":"2025-02-14T18:22:45Z","message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","test-plan","v9.0.0","Team:Detections
and Resp","Team: SecuritySolution","Team:Detection Rule
Management","Feature:Prebuilt Detection
Rules","backport:version","v8.18.0","v9.1.0","v8.19.0"],"title":"[Security
Solution] Refactor prebuilt rule customization test plans, part
1","number":211300,"url":"https://github.com/elastic/kibana/pull/211300","mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},"sourceBranch":"main","suggestedTargetBranches":["9.0","8.18","8.x"],"targetPullRequestStates":[{"branch":"9.0","label":"v9.0.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"8.18","label":"v8.18.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/211300","number":211300,"mergeCommit":{"message":"[Security
Solution] Refactor prebuilt rule customization test plans, part 1
(#211300)\n\n**Epic:**
https://github.com/elastic/kibana/issues/174168\r\n**Partially
addresses:**\r\nhttps://github.com//issues/202068,\r\nhttps://github.com//issues/202078,\r\nhttps://github.com//issues/202079\r\n\r\n##
Summary\r\n\r\nWe're cleaning up and refactoring our existing test plans
for prebuilt\r\nrule customization, upgrade, and export/import
workflows.\r\n\r\nSpecifically, in this PR we're consistently:\r\n\r\n-
Changing the file names and test plan titles.\r\n- Adding or expanding
test plan summaries.\r\n- Regenerating tables of contents using the
[Markdown All
in\r\nOne](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)\r\nVS
Code extension.\r\n\r\nNo \"functional\" changes have been made to any
test plans, such as\r\nadding, removing, or updating any
scenarios.\r\n\r\nThis refactoring prepares the test plans for being
\"functionally\"\r\nchanged and improved in follow-up PRs. For example,
we're going to cover\r\nthe logic described in
https://github.com/elastic/kibana/issues/210358\r\nand address any other
gaps in
coverage.","sha":"9600de4338edc123dbac7c2cb3403ede2f016752"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Georgii Gorbachev <georgii.gorbachev@elastic.co>

…part 2 (#211472)

**Epic:** #174168
**Partially addresses:**
#202068,
#202078,
#202079
**Follow-up to:** #211300

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, this PR:

- Creates an "entrypoint" file that should help navigate all the test
plans for prebuilt rules.
- Creates a file for keeping common information about prebuilt rules
that can be shared between the test plans.
- Extracts duplicated terminology to the file with common information.
- Extracts duplicated assumptions to the file with common information.
- Extracts duplicated non-functional requirements to the file with
common information.
- Adds user stories to each test plan.
- Updates links to tickets in every test plan.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in #210358
and address any other gaps in coverage.

## Review tip

It might be easier to review this PR commit-by-commit as each of them
contains logically cohesive changes.

…part 2 (elastic#211472)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079
**Follow-up to:** elastic#211300

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, this PR:

- Creates an "entrypoint" file that should help navigate all the test
plans for prebuilt rules.
- Creates a file for keeping common information about prebuilt rules
that can be shared between the test plans.
- Extracts duplicated terminology to the file with common information.
- Extracts duplicated assumptions to the file with common information.
- Extracts duplicated non-functional requirements to the file with
common information.
- Adds user stories to each test plan.
- Updates links to tickets in every test plan.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

## Review tip

It might be easier to review this PR commit-by-commit as each of them
contains logically cohesive changes.

(cherry picked from commit 786df79)

…part 2 (elastic#211472)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079
**Follow-up to:** elastic#211300

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, this PR:

- Creates an "entrypoint" file that should help navigate all the test
plans for prebuilt rules.
- Creates a file for keeping common information about prebuilt rules
that can be shared between the test plans.
- Extracts duplicated terminology to the file with common information.
- Extracts duplicated assumptions to the file with common information.
- Extracts duplicated non-functional requirements to the file with
common information.
- Adds user stories to each test plan.
- Updates links to tickets in every test plan.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

## Review tip

It might be easier to review this PR commit-by-commit as each of them
contains logically cohesive changes.

(cherry picked from commit 786df79)

…part 2 (elastic#211472)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079
**Follow-up to:** elastic#211300

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, this PR:

- Creates an "entrypoint" file that should help navigate all the test
plans for prebuilt rules.
- Creates a file for keeping common information about prebuilt rules
that can be shared between the test plans.
- Extracts duplicated terminology to the file with common information.
- Extracts duplicated assumptions to the file with common information.
- Extracts duplicated non-functional requirements to the file with
common information.
- Adds user stories to each test plan.
- Updates links to tickets in every test plan.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

## Review tip

It might be easier to review this PR commit-by-commit as each of them
contains logically cohesive changes.

(cherry picked from commit 786df79)

…part 1 (elastic#211300)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, in this PR we're consistently:

- Changing the file names and test plan titles.
- Adding or expanding test plan summaries.
- Regenerating tables of contents using the [Markdown All in
One](https://marketplace.visualstudio.com/items?itemName=yzhang.markdown-all-in-one)
VS Code extension.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

…part 2 (elastic#211472)

**Epic:** elastic#174168
**Partially addresses:**
elastic#202068,
elastic#202078,
elastic#202079
**Follow-up to:** elastic#211300

## Summary

We're cleaning up and refactoring our existing test plans for prebuilt
rule customization, upgrade, and export/import workflows.

Specifically, this PR:

- Creates an "entrypoint" file that should help navigate all the test
plans for prebuilt rules.
- Creates a file for keeping common information about prebuilt rules
that can be shared between the test plans.
- Extracts duplicated terminology to the file with common information.
- Extracts duplicated assumptions to the file with common information.
- Extracts duplicated non-functional requirements to the file with
common information.
- Adds user stories to each test plan.
- Updates links to tickets in every test plan.

No "functional" changes have been made to any test plans, such as
adding, removing, or updating any scenarios.

This refactoring prepares the test plans for being "functionally"
changed and improved in follow-up PRs. For example, we're going to cover
the logic described in elastic#210358
and address any other gaps in coverage.

## Review tip

It might be easier to review this PR commit-by-commit as each of them
contains logically cohesive changes.