[8.19] (backport #18386) Backport smart exhaustive tests

[mergify]

Backports the following commits:

bf89f43 (HEAD, upstream/main) chore: remove test file for exhaustive tests and normalise github commands (#18384)
02aa5e1 bk(smart exhaustive tests): tune the steps to support GH comments and changesets (#18383)
be64ebf bk: fix regex and add new file (#18382)
fc9ad7f feat(ci): support exhaustive tests for PRs (code changes or GH comment) (#18327)

To solve:

https://buildkite.com/elastic/logstash-smart-exhaustive-tests-pipeline/builds/32#019a3b6c-873e-4817-8fe1-4552c0fba68a

2025-10-31 10:59:54 PDT
Running agent environment hook
2025-10-31 10:59:56 PDT
Preparing working directory
2025-10-31 11:00:00 PDT
Running commands
2025-10-31 11:00:00 PDT
$ buildkite-agent pipeline upload .buildkite/smart_exhaustive_tests_pipeline.yml
2025-10-31 11:00:00 PDT
2025-10-31 18:00:00 INFO   Reading pipeline configs from [".buildkite/smart_exhaustive_tests_pipeline.yml"]
2025-10-31 11:00:00 PDT
buildkite-agent: fatal: failed to read file: open .buildkite/smart_exhaustive_tests_pipeline.yml: no such file or directory
2025-10-31 11:00:00 PDT
🚨 Error: The command exited with status 1
2025-10-31 11:00:00 PDT
user command error: exit status 1
```<hr>This is an automatic backport of pull request #18386 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 906d5bd has failed:

On branch mergify/bp/8.19/pr-18386
Your branch is up to date with 'origin/8.19'.

You are currently cherry-picking commit 906d5bd6.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	new file:   .buildkite/smart_exhaustive_tests_pipeline.yml
	modified:   catalog-info.yaml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .buildkite/pull-requests.json

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 2eee775

History

• 💛 Build #3809 was flaky f5c4930

cc @donoghuc

[mergify]

This pull request has not been merged yet. Could you please review and merge it @donoghuc? 🙏

[donoghuc]

Thanks for resolving the merge conflict @v1v ❤️