Ensure root CA certificate secret inherits cluster metadata

[joerocklin]

Add support for propagating PostgresCluster metadata (labels and annotations) to the root CA certificate secret. This allows users to apply custom labels and annotations defined in the cluster spec to the shared root certificate secret.

Changes:

• Updated reconcileRootCertificate to merge cluster metadata into the root certificate secret's labels and annotations
• Updated testCluster helper to include metadata for testing purposes
• Added tests to verify labels and annotations are properly set on the root CA secret

Checklist:

• [x] Have you added an explanation of what your changes do and why you'd like them to be included?
• [ ] Have you updated or added documentation for the change, as applicable?
• [ ] Have you tested your changes on all related environments with successful results, as applicable?
  • [x] Have you added automated tests?

Type of Changes:

• [ ] New feature
• [x] Bug fix
• [ ] Documentation
• [x] Testing enhancement
• [ ] Other

What is the current behavior (link to any open issues here)?

#4324

What is the new behavior (if this is a feature change)?

• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Ensures that the cluster spec.metadata fields are applied to the PGO

Other Information: