Truncate long labels with ellipsis in labels page

## What does this MR do?
Fixes #22953, where long labels overlaps into the description field in the labels page. Truncates long labels with ellipsis. Labels that fit are unaffected.

## Are there points in the code the reviewer needs to double check?
No

## Why was this MR needed?
Fixes #22953.

## Screenshots (if relevant)
Existing behavior:
![image](/uploads/4d85730fe9d039d91036d09bf892d9f2/image.png)

With the change:
![desktop](/uploads/6866389cc3a1e2af5c2def59536a2a7c/desktop.png)
![mobile](/uploads/3d1fbb4a3470abefdd3670f7a794d2a8/mobile.png)

## Does this MR meet the acceptance criteria?
- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?
Closes #22953

See merge request !6725