Additional rounded label fixes

## What does this MR do?

fixes some UI bugs for the change to rounded labels

## Are there points in the code the reviewer needs to double check?
-

## Why was this MR needed? / Screenshots (if relevant)

before:
![image](/uploads/ce359bb021fee324156f050b3f848c2e/image.png)

after:
![image](/uploads/a5f0d536db3efdce4ff994deb0d73081/image.png)
these now have full rounded border-radius as well :)
![image](/uploads/d331eae2c32dd043766b4148f9ad88e9/image.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support 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 it does - 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?

-

See merge request !8136