Switch to using admin for project rolebindings

What does this MR do?

Switch to using admin for project rolebindings (Gated behind a disbled feature flag initially)

This enables CI to create roles and rolebindings within that namespace (e.g. installing helm charts, tkuah/minimal-ruby-app!4 (closed))

Related issue: #31113 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.