Fix file links on project page Files view

## What does this MR do?

Fix the project show page when the default view is set to Files so that the links work.

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

I can't figure out what caused this to break 😕 

## What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-com/support-forum/issues/959.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md) (N/A)
- [x] API support added (N/A)
- Tests
  - [x] Added for this feature/bug
  - [ ] 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 !5933