[9.0](backport #42569) metricbeat: Update beat module with apm-server tail sampling monitoring metrics fields

[mergify]

Proposed commit message

Update metricbeat beat module mapping to add back missing apm-server tail sampling montioring metrics fields.

The fields were missed in #40127

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.

Disruptive User Impact

Author's Checklist

• [ ]

How to test this PR locally

• Start apm-server with monitoring
• Start standalone metricbeat with beat module
• Confirm that fields are mapped correctly in metricbeat-* data stream

Related issues

• Part of monitoring: apm-server not shiping tbs monitoring metrics apm-server#14247

Use cases

Screenshots

Logs

---

This is an automatic backport of pull request #42569 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 9134522 has failed:

On branch mergify/bp/9.0/pr-42569
Your branch is up to date with 'origin/9.0'.

You are currently cherry-picking commit 9134522bc.
  (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:   CHANGELOG.next.asciidoc
	modified:   metricbeat/docs/fields.asciidoc
	modified:   metricbeat/module/beat/_meta/fields.yml
	modified:   metricbeat/module/beat/stats/_meta/fields.yml
	modified:   metricbeat/module/beat/stats/_meta/test/apm-server.stats.712.json

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   metricbeat/module/beat/fields.go

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

[botelastic]

This pull request doesn't have a Team:<team> label.

[mergify]

This pull request is now in conflicts. Could you fix it? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b mergify/bp/9.0/pr-42569 upstream/mergify/bp/9.0/pr-42569
git merge upstream/9.0
git push upstream mergify/bp/9.0/pr-42569