[Meta] Refactor Rule Loader and Validation for Optimizations

[Mikaayenson]

Parent Epic (If Applicable)

https://github.com/elastic/security-team/issues/8718

Meta Summary

The detection rules loader is extremely slow. While we're planning on tackling the loader for potential optimizations, we should clean up some of the warnings and error messages.

Estimated Time to Complete

1-2 sprints

Potential Blockers

None

Tasklist

### Meta Tasks
- [ ] Provide Week 1 Update Comment
- [ ] Provide Week 2 Update or Closeout Comment
- [ ] https://github.com/elastic/detection-rules/issues/2609
- [ ] https://github.com/elastic/detection-rules/issues/2606
- [ ] https://github.com/elastic/detection-rules/issues/3195

Resources / References

May be related to the work completed in #3512

[botelastic]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[botelastic]

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