158528: roachtest: add Datadog integration for test log ingestion r=golgeek a=williamchoe3

Previously, we didn't have an easy way to do full text search across CI test runs across different TC Build Configurations and branches. To do that, you would have to download the artifacts for what you wanted to search for.

This change adds a datadog package that uploads test.log files to Datadog during test cleanup on master and release branches. The implementation scans the log file serially and uses a worker pool to upload log entries in batches of 1000 using the Datadog API client. Each log entry is tagged with test metadata (test name, owner, cloud, platform, version) and includes attributes for higher cardinality fields (cluster name, build number, result, duration). See comments for more details.

The entry point for datadog upload in `roachtest` will be during the post step test in `test_runner.go.`  Added a new roachtest flag `datadog-always-upload` for e2e testing on a non release branch.  Modified TC build scripts to pass new env vars and the teamcity build properties file.

160526: sql: fix TestUnsplitRanges to work with external test tenants r=rafiss a=rafiss

Previously, TestUnsplitRanges was skipped in external test tenant mode because it scanned meta ranges directly and performed AdminSplit/ AdminUnsplit operations that external tenants cannot do.

This commit fixes the test by:
1. Using the system layer's DB for meta range operations (scanning meta ranges, checking sticky bits, splitting ranges) since tenants cannot access meta ranges directly.
2. Using the application layer's DB for table data operations which tenants can access.
3. Granting the CanAdminUnsplit capability to the external tenant so the GC job can unsplit ranges after dropping tables/indexes.

Resolves: #142388
Epic: CRDB-48944

Release note: None

160549: build: remove unused publish script for no-telemetry release r=celiala a=rail

Remove the unused script, because we no longer use it.

Epic: none
Release note: none

Co-authored-by: William Choe <williamchoe3@gmail.com>
Co-authored-by: Rafi Shamim <rafi@cockroachlabs.com>
Co-authored-by: Rail Aliiev <rail@iqchoice.com>