<!--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=587134) </details> <!--IssueSummary end--> Implement update service for v2 approval rules. Requirements: - Check authorisation - Find the approval rule by ID - Update rule attributes (name, approvals_required) - Update user approvers (if user_ids provided) - Update group approvers (if group_ids provided) - Handle `remove_hidden_groups` parameter (filter inaccessible groups) - Return ServiceResponse with success/error Reference: [POC implementation](https://gitlab.com/gitlab-org/gitlab/-/blob/e8e6a5dfaf484ebd3ccd8b06029a1ddfbbb5ecf5/ee/app/services/merge_requests/v2_approval_rules/update_service.rb) in `poc/v2-approval-rules-complete` branch