Fix teleporting emoji (MR description instead of comment)

What does this MR do?

Fixes a bug that causes MR discussion emojis to be added to the description instead of a comment.

Are there points in the code the reviewer needs to double check?

Previous review is on https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16963

Why was this MR needed?

See #35530 (closed)

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?

Closes #35530 (closed)