Remove suggested colors hover underline

## What does this MR do?
* Removes the blue hover underline for the suggested color containers 
* Added `cursor: pointer` to the suggested color containers  

## Are there points in the code the reviewer needs to double check?
Shouldn't be 😄 

## Why was this MR needed?
Improves UI

## Screenshots (if relevant)
Before:
![DS48AvgSVX](/uploads/0077e7a5837c8ce9fe2493ad6a42a018/DS48AvgSVX.gif)

After:
![olZzS68WNr](/uploads/4e0ae808c69942a528f1303df8cddeae/olZzS68WNr.gif)

## Does this MR meet the acceptance criteria?

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

## What are the relevant issue numbers?
Closes #21792

See merge request !6165