Disable RBAC on Prometheus values.yml

What does this MR do?

Disable RBAC on Prometheus values.yml, since the default value was changed

Why was this MR needed?

To enable Prometheus installation again from Cluster applications

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Review
  • Has been reviewed by Backend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #43621 (closed)