<!--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=378406) </details> <!--IssueSummary end--> When GitLab Migration is used via UI it only shows top-level groups a user has owner access to, which can be limiting whenever a user wants to migrate a subgroup instead. It's possible to migrate a subgroup if GitLab Migration API is used. We should update Gitlab Migration UI to present all groups a user has owner access to, instead of top-level groups only, so that the functionality is identical between UI and API.