Merge branch '19814-regression-snippet-pagination-on-user-page-leads-to-raw-json-instead-of-normal-webpage' into 'master'

Fix pagination on user snippets page

## What does this MR do?

Copy the pagination code from projects -> snippets on a user's profile page.

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

Don't think so.

## Why was this MR needed?

It was a bug!

## Screenshots (if relevant)

(I set the pagination to two per page for this, because I'm lazy.)

![Snippets](/uploads/986abd8608cda1cd76416e55b2c3a3ba/Snippets.gif)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [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 #19814.

See merge request !6179