Fix label links update on project transfer

Why was this MR needed?

When transferring a project, label links pointing to the old group labels are updated. There was a bug in the query which caused that label links (for group labels only, not project labels) were updated for all projects in the group.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Review
  • Has been reviewed by Backend

What are the relevant issue numbers?

Closes #44158 (closed)