Explore adding branch name to accessible link labels
<!--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=567804) </details> <!--IssueSummary end--> @psjakubowska identified an opportunity to improve repository graph link labels by [adding branch names](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/203014#note_2723764391) in [MR 203014](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/203014). Adding the branch name should be tested with screen readers and determine if adding this information makes the label announcement too long, or if the added length is valuable. Success may be adding the branch name where appropriate. Success may also be closing this issue as `won't fix` because we're happy with the accessible label as.
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