Remove libbeat/keystore, libbeat/common/kubernetes and libbeat/common/docker

[kvch]

What does this PR do?

This PR removes libbeat/keystore and imports it from github.com/elastic/elastic-agent-libs/keystore instead. Futhermore, docker and kubernetes functions are imported from elastic-agent-autodiscover.

I am not fixing the linter issues.

Why is it important?

We no longer have to maintain the code in two places.

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.

[elasticmachine]

❕ Build Aborted

There is a new build on-going so the previous on-going builds have been aborted.

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Build stats

• Start Time: 2022-05-16T11:58:25.406+0000

• Duration: 77 min 58 sec

Test stats 🧪

Test	Results
Failed	0
Passed	351
Skipped	116
Total	467

Steps errors

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metricbeat-goIntegTest - mage goIntegTest

• Took 30 min 7 sec . View more details here
• Description: mage goIntegTest

metricbeat-goIntegTest - mage goIntegTest

• Took 20 min 19 sec . View more details here
• Description: mage goIntegTest

Error signal

• Took 0 min 0 sec . View more details here
• Description: Error 'org.jenkinsci.plugins.workflow.steps.FlowInterruptedException'

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[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 move-keystore upstream/move-keystore
git merge upstream/main
git push upstream move-keystore

[elasticmachine]

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

[fearful-symmetry]

RIP the linter.

Otherwise, changes seem good.

[kvch]

/test metricbeat

[elasticmachine]

💚 Flaky test report

Tests succeeded.

🤖 GitHub comments

To re-run your PR in the CI, just comment with:

• /test : Re-trigger the build.

• /package : Generate the packages and run the E2E tests.

• /beats-tester : Run the installation tests with beats-tester.

• run elasticsearch-ci/docs : Re-trigger the docs validation. (use unformatted text in the comment!)