Make branches sortable without push permission

## What does this MR do?

Make branches on the branches page sortable without push permission.

## Why was this MR needed?

Sorting branches (a readonly action) required push permission which does not make sense.

## What are the relevant issue numbers?

fixes #18678

## Screenshots

### Before

![before](/uploads/d77d0be2599481b815cb2ef1f9c33a15/before.png)

### After

![after](/uploads/edbcf9d5ec4b2650866742ead0c2c1ed/after.png)


See merge request !5462