[7.17](backport #40560) Add pre-commit step to beats pipelines

[mergify]

Proposed commit message

Added pre-commit check to beats pipelines to validate if no merge-conflicts exist.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Related issues

• Relates: https://github.com/elastic/ingest-dev/issues/3350

Logs

Buildkite builds: https://buildkite.com/elastic/beats/builds?branch=oakrizan%3Aadd-pre-commit-plugin

---

This is an automatic backport of pull request #40560 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of ecc5215 has failed:

On branch mergify/bp/7.17/pr-40560
Your branch is up to date with 'origin/7.17'.

You are currently cherry-picking commit ecc521545d.
  (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:
	modified:   .buildkite/auditbeat/auditbeat-pipeline.yml
	modified:   .buildkite/deploy/kubernetes/deploy-k8s-pipeline.yml
	modified:   .buildkite/filebeat/filebeat-pipeline.yml
	modified:   .buildkite/heartbeat/heartbeat-pipeline.yml
	modified:   .buildkite/metricbeat/pipeline.yml
	modified:   .buildkite/packetbeat/pipeline.packetbeat.yml
	modified:   .buildkite/winlogbeat/pipeline.winlogbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.auditbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.dockerlogbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.filebeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.heartbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.libbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.metricbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.osquerybeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.packetbeat.yml
	modified:   .buildkite/x-pack/pipeline.xpack.winlogbeat.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .buildkite/libbeat/pipeline.libbeat.yml

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

[oakrizan]

lgtm, minor conflict in env definition in lebbeat