Merge branch 'fix/confusing-blocked-user-description' into 'master'

Fix confusing description of a blocked user.

## What does this MR do?
Rewrite confusing description of a blocked user in admin settings. If someone is blocked, the same message is displayed as if he is unblocked.

## Are there points in the code the reviewer needs to double check?
No.

## Why was this MR needed?
Because it seems that this is a cosmetic bug.

## What are the relevant issue numbers?
None.

## Screenshots (if relevant)
![blocked_user](/uploads/0782a82760ae19661d69c63a97daaf33/blocked_user.png)

## 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)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [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 !5582

CHANGELOG

@@ -40,6 +40,7 @@ v 8.11.0 (unreleased)
   - Remove `search_id` of labels dropdown filter to fix 'Missleading URI for labels in Merge Requests and Issues view'. !5368 (Scott Le)
   - Load project invited groups and members eagerly in `ProjectTeam#fetch_members`
   - Bump gitlab_git to speedup DiffCollection iterations
+  - Rewrite description of a blocked user in admin settings. (Elias Werberich)
   - Make branches sortable without push permission !5462 (winniehell)
   - Check for Ci::Build artifacts at database level on pipeline partial
   - Convert image diff background image to CSS (ClemMakesApps)

app/views/admin/users/show.html.haml

@@ -140,12 +140,10 @@
           .panel-heading
             This user is blocked
           .panel-body
-            %p Blocking user has the following effects:
+            %p A blocked user cannot:
             %ul
-              %li User will not be able to login
-              %li User will not be able to access git repositories
-              %li Personal projects will be left
-              %li Owned groups will be left
+              %li Log in
+              %li Access Git repositories
             %br
             = link_to 'Unblock user', unblock_admin_user_path(@user), method: :put, class: "btn btn-info", data: { confirm: 'Are you sure?' }
       - else