[9.0] (backport #19188) fix(packaging): slack notifications and DRA branch for PRs

[mergify]

Motivation/summary

Improve:

• No more ad hoc post-checkout after using the BK PR Bot
• No need to run the pre-command hook when running the upload step.

Fixes issues after using the BK PR Bot:

• Slack notifications (only for main and release branches)
• Wrong DRA Branch

Otherwise it only supports main, release branches and feature branches, but no forked PRs

Checklist

• Update CHANGELOG.asciidoc
• Documentation has been updated

For functional changes, consider:

• Is it observable through the addition of either logging or metrics?
• Is its use being published in telemetry to enable product improvement?
• Have system tests been added to avoid regression?

How to test these changes

Related issues

---

This is an automatic backport of pull request #19188 done by [Mergify](https://mergify.com).

[github-actions]

🤖 GitHub comments

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Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[mergify]

This pull request has been removed from the queue for the following reason: checks failed.

The merge conditions cannot be satisfied due to failing checks:

• ❌ system-test

You can check the last failing draft PR here: #19220.

You may have to fix your CI before adding the pull request to the queue again.
If you update this pull request, to fix the CI, it will automatically be requeued once the queue conditions match again.
If you think this was a flaky issue instead, you can requeue the pull request, without updating it, by posting a @mergifyio requeue comment.

[kruskall]

@v1v I think you need to sign the commits since it was changed iiuc

[v1v]

@v1v I think you need to sign the commits since it was changed iiuc

We solved the issue of unsigned commits with mergify, therefore mergify should fix this, but the merge-queue is failing in the CI

• https://github.com/elastic/apm-server/actions/runs/18653517949/job/53176871615

[mergify]

queue

🛑 The pull request has been removed from the queue default

The merge conditions cannot be satisfied due to failing checks.

You can take a look at Queue: Embarked in merge queue check runs for more details about the failure.

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: e2f8ae3

History

• 💛 Build #6597 was flaky d7a9a76

cc @v1v