[8.18](backport #47089) [9.1] Sync mock-es library with main

[mergify]

Proposed commit message

Backporting tests that rely on a recent version of mock-es to other branches is currently impossible due to a breaking change in mock-es api.NewHandler. This change backports the related mock-es changes.

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

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This is an automatic backport of pull request #47089 done by Mergify.

[mergify]

Cherry-pick of 240cb89 has failed:

On branch mergify/bp/8.18/pr-47089
Your branch is up to date with 'origin/8.18'.

You are currently cherry-picking commit 240cb8905.
  (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:   NOTICE.txt
	both modified:   go.mod
	both modified:   go.sum
	both modified:   libbeat/tests/integration/elasticsearch_test.go
	both modified:   libbeat/tests/integration/framework.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

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)