Fix warning messages for promoting labels and milestones

What does this MR do?

Fixes the warning messages for then labels and milestones get promoted

Screenshots (if relevant)

Labels

Milestones

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

closes #42900 (closed)