[9.0] (backport #17872) fix: do not try to create apm-serve registry if it exists

[mergify]

Motivation/summary

apm-server registry could already exist, causing a failure on agent reload when trying to be recreated

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 #17872 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of b17e61d has failed:

On branch mergify/bp/9.0/pr-17872
Your branch is up to date with 'origin/9.0'.

You are currently cherry-picking commit b17e61d6.
  (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)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   internal/beater/telemetry.go

no changes added to commit (use "git add" and/or "git commit -a")

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

[github-actions]

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