<!--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> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=32307) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=32307) </details> <!--IssueSummary end--> ## Summary We recently [added validation](https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/16216) to prevent users creating approver groups with the same name. As part of this, we should also create database-level constraints and migrate existing data that have duplicates. See: https://gitlab.com/gitlab-org/gitlab/merge_requests/16216#note_213395600 ## Improvements Prevents inconsistent data state at the database level. ## Risks Data migration might be tricky? ## Involved components <!-- List files or directories that will be changed by the refactoring. --> ## Optional: Intended side effects <!-- If the refactoring involves changes apart from the main improvements (such as a better UI), list them here. It may be a good idea to create separate issues and link them here. --> ## Optional: Missing test coverage <!-- If you are aware of tests that need to be written or adjusted apart from unit tests for the changed components, please list them here. -->