Fix repo title alignment

## What does this MR do?
Adds an extra pixel margin to the hamburger button so that it matches the baseline of the repo title

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

## Why was this MR needed?
Resolve UI Inconsistency

## What are the relevant issue numbers?
Closes #21408 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-25_at_8.44.11_PM](/uploads/e18241f3f025c501427f28d9040ca898/Screen_Shot_2016-08-25_at_8.44.11_PM.png)

After:
![Screen_Shot_2016-08-25_at_8.43.45_PM](/uploads/03eca5df535af12eff7b79109a6b6f23/Screen_Shot_2016-08-25_at_8.43.45_PM.png)

## 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 [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)

See merge request !6046