Fix GitHub project import visibility

What does this MR do?

This fixes the common case of importing a public GitHub project into a namespace with a visibility level other than PUBLIC.

This likely does not address all issues in #47327 (moved).

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

Performance and testing

This should not have any noticeable performance impact.

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

Security

N/A