<!--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=340637) </details> <!--IssueSummary end--> Users should have a way through the UI or the API to stop an ongoing migration. Similar to how we can stop GitLab CI jobs. The UX is probably straightforward. Either API or UI. The technical solution still needs to be discussed. /cc @georgekoltsov FYI @hdelalic