Validate management project is in same namespace

What does this MR do?

Validate that we can only choose management project from group or child groups of cluster.

This also prevents authorization surprises where a cluster can be used outside of a group. (e.g. cluster in company group used in other namespaces).

Part of #32810 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation created/updated or follow-up review issue created
• 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.
• [-] Tested in all supported browsers