[9.0](backport #44831) otel: fix service.name for beats receivers

[mergify]

Proposed commit message

Beats receivers currently use the hostname as the "service.name" logger field. Adjust it to reflect the beat name for consistency with standard beats.

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

• Closes Beats receivers should emit the same log attributes as beats processes #44774

  ---

  This is an automatic backport of pull request otel: fix service.name for beats receivers #44831 done by Mergify.

[mergify]

Cherry-pick of df3dcad has failed:

On branch mergify/bp/9.0/pr-44831
Your branch is up to date with 'origin/9.0'.

You are currently cherry-picking commit df3dcadbd.
  (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:   libbeat/otelbeat/oteltest/oteltest.go
	modified:   x-pack/libbeat/cmd/instance/beat.go
	modified:   x-pack/metricbeat/mbreceiver/receiver_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   x-pack/filebeat/fbreceiver/receiver_test.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