Cleanup redundant data after migrating vanilla K8s tests

[gurevichdmitry]

Summary of your changes

This PR performs cleanup tasks of the testing infrastructure following the migration of vanilla Kubernetes tests to a new format. Specifically, it includes the removal of outdated test cases, unnecessary test data, and folders that are no longer relevant. Additionally, the k8s CI workflow has been updated.

• Old test cases removed: All outdated test cases are identified and safely removed from the codebase.
• Unnecessary test data removed: Redundant test data is cleaned up, ensuring only relevant and up-to-date data remains.
• Folder cleanup: Unnecessary folders related to old tests are deleted, optimizing the repository structure.
• GitHub CI workflow updated: The GitHub CI workflow is modified to reflect the changes introduced by the migration.
• Documentation Updated: Any relevant documentation is updated to reflect the changes made during the cleanup.
• Successful CI tests: After cleanup, the CI workflow should successfully run tests on the modified codebase without errors.

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Related Issues

Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary README/documentation (if appropriate)

Introducing a new rule?

• Generate rule metadata using this script
• Add relevant unit tests
• Generate relevant rule templates using this script, and open a PR in elastic/packages/cloud_security_posture

[mergify]

This pull request does not have a backport label. Could you fix it @gurevichdmitry? 🙏
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.

[github-actions]

❌ No tests were run ❌

[github-actions]

📊 Allure Report - 💚 No failures were reported.

Result	Count
🟥 Failed	0
🟩 Passed	359
⬜ Skipped	33

[kubasobon]

🚀