Remove dependency on libbeat

[kvch]

What does this PR do?

• Moves golangci-lint to macos workers, so CGO can be enabled for the jobs
• Adds refactoring of metrics setup, so it no longer depends on libbeat
• NOTICE.txt file is updated with new dependencies
• Several minor issues (reported by golanglint-ci) are fixed

Why is it important?

This is the last step to remove libbeat from the dependencies of Elastic Agent.

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.

[mergify]

This pull request does not have a backport label. Could you fix it @kvch? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-v./d./d./d is the label to automatically backport to the 8./d branch. /d is the digit

NOTE: backport-skip has been added to this pull request.

[elasticmachine]

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Build stats

• Start Time: 2022-04-28T08:00:40.810+0000

• Duration: 36 min 27 sec

Test stats 🧪

Test	Results
Failed	0
Passed	3849
Skipped	21
Total	3870

🤖 GitHub comments

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[ph]

/test

[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 remove-libbeat upstream/remove-libbeat
git merge upstream/main
git push upstream remove-libbeat

[ph]

Thanks @kvch

[kvch]

/test

[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 remove-libbeat upstream/remove-libbeat
git merge upstream/main
git push upstream remove-libbeat

[kvch]

/test