Unlink should only show currently linked merge requests
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=578835) </details> <!--IssueSummary end--> The following discussion from !207136 should be addressed: - [ ] @mle started a [discussion](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/207136#note_2851627498): (+2 comments) > @ptalbert **issue** `/unlink` should only show the currently linked merge requests > > In this merge request I only linked the "second change" merge request so that's the only one that should be listed. > ![CleanShot_2025-10-29_at_09.49.26](/uploads/31ae5042cfbca5b3441bbb466b4314db/CleanShot_2025-10-29_at_09.49.26.png) > > For refernece, this functionality is correctly done in work items https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183102+ Also `/unlink` should not appear if there are no dependent merge requests.https://gitlab.com/gitlab-org/gitlab/-/merge_requests/207136#note_2851627500
issue