[auditbeat] Make auditbeat resumeable when config is locked and immutable is set

[marc-gr]

What does this PR do?

If auditd config is locked and the immutable option is set, all the configuration setup is ignored to be able to resume events processing onces the pid is changed.

Why is it important?

This way auditbeat can be stopped and restarted without requiring a system restart as far as the configuration does not need to change.

Chnagelog not added since this is modifying a feature added for 8.4 that is still not released.

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]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[elasticmachine]

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• Start Time: 2022-07-26T15:57:52.929+0000

• Duration: 53 min 6 sec

Test stats 🧪

Test	Results
Failed	0
Passed	573
Skipped	81
Total	654

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[adriansr]

LGTM