Fix branches page dropdown sort initial state

## What does this MR do?
Add 'Name' as the initial state for the branches dropdown filter

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

## Why was this MR needed?
Prevent dropdown from being rendered without an initial state

## What are the relevant issue numbers?
Closes #20753 

## Screenshots (if relevant)
Before:
![Screen_Shot_2016-08-10_at_2.26.59_PM](/uploads/e13725c90d1e870e0b08c3bff9234c4e/Screen_Shot_2016-08-10_at_2.26.59_PM.png)

After:
![Screen_Shot_2016-08-10_at_2.26.45_PM](/uploads/cd4957902ee1ebb74ac6e93b18c8ed02/Screen_Shot_2016-08-10_at_2.26.45_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 !5761