…t variables (elastic#155829)

## Summary

Closes [elastic#155812](elastic#155812)

In elastic#155384, detection rules were
switched to support per-alert actions. When passing the context
variable, it was suggested that we should be calling formatAlert to
format the alert for notifications, however doing that causes some test
failures because formatAlert is fairly heavyweight and bunch of tests
were timing out.

Thanks to @marshallmain we have this much faster `expandDottedObject`
that solves the issue with the very slow `formatAlert`.

(cherry picked from commit 8f59720)

…context variables (#155829) (#156009)

# Backport

This will backport the following commits from `main` to `8.8`:
- [[Security Solution][Alerts] Format alerts for per-alert action
context variables
(#155829)](#155829)

<!--- Backport version: 8.9.7 -->

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

<!--BACKPORT [{"author":{"name":"Ievgen
Sorokopud","email":"ievgen.sorokopud@elastic.co"},"sourceCommit":{"committedDate":"2023-04-26T16:16:41Z","message":"[Security
Solution][Alerts] Format alerts for per-alert action context variables
(#155829)\n\n## Summary\r\n\r\nCloses
[#155812](https://github.com/elastic/kibana/issues/155812)\r\n\r\nIn
#155384, detection rules
were\r\nswitched to support per-alert actions. When passing the
context\r\nvariable, it was suggested that we should be calling
formatAlert to\r\nformat the alert for notifications, however doing that
causes some test\r\nfailures because formatAlert is fairly heavyweight
and bunch of tests\r\nwere timing out.\r\n\r\nThanks to @marshallmain we
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Solution][Alerts] Format alerts for per-alert action context variables
(#155829)\n\n## Summary\r\n\r\nCloses
[#155812](https://github.com/elastic/kibana/issues/155812)\r\n\r\nIn
#155384, detection rules
were\r\nswitched to support per-alert actions. When passing the
context\r\nvariable, it was suggested that we should be calling
formatAlert to\r\nformat the alert for notifications, however doing that
causes some test\r\nfailures because formatAlert is fairly heavyweight
and bunch of tests\r\nwere timing out.\r\n\r\nThanks to @marshallmain we
have this much faster `expandDottedObject`\r\nthat solves the issue with
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Solution][Alerts] Format alerts for per-alert action context variables
(#155829)\n\n## Summary\r\n\r\nCloses
[#155812](https://github.com/elastic/kibana/issues/155812)\r\n\r\nIn
#155384, detection rules
were\r\nswitched to support per-alert actions. When passing the
context\r\nvariable, it was suggested that we should be calling
formatAlert to\r\nformat the alert for notifications, however doing that
causes some test\r\nfailures because formatAlert is fairly heavyweight
and bunch of tests\r\nwere timing out.\r\n\r\nThanks to @marshallmain we
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the very slow
`formatAlert`.","sha":"8f597207a222f02b1c7664bc555a9f6e744bc4aa"}}]}]
BACKPORT-->

Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>