Closes #21417

add feature test

add feature test

add feature test

remove test to builds_spec

remove feature test to builds_spec

remove feature test to builds_spec

add changes to methods and remove FactoryGirl

add changes to methods and remove FactoryGirl

adding changes to test and js file

changes grammar

update changelog

rename file name

update files after review

update files after review

update files after review

show variables on-click

show variables on-click

show variables on-click

remove = and add new js classes into sidebar.scss

show variables by clicking button

show variables by clicking button

show variables by clicking button

show variables by clicking button

use id for a class

add nicescroll

add nicescroll

```
 Failure/Error: namespace.human_name + ' / ' + name

     ActionView::Template::Error:
       undefined method `+' for nil:NilClass
     # ./app/models/project.rb:807:in `name_with_namespace'
     # ./app/views/layouts/project.html.haml:1:in `_app_views_layouts_project_html_haml___2918737809244135908_70160161538920
'
     # ./app/controllers/projects/commit_controller.rb:23:in `show'
     # ./lib/gitlab/request_profiler/middleware.rb:15:in `call'
     # ./lib/gitlab/middleware/go.rb:16:in `call'
     # ./lib/gitlab/middleware/static.rb:9:in `call'
     # ------------------

     # --- Caused by: ---
     # NoMethodError:
     #   undefined method `+' for nil:NilClass
     #   ./app/models/project.rb:807:in `name_with_namespace'
```

Capybara's `click_link` method doesn't actually wait for the page to reload.
When the `expand_all_diffs` parameter is used, we need to search for unique
elements that appear to ensure that the page has actually reloaded.

Closes #21841

- Added an extra new line to the prepend of the Close message

Fixes #21710

If `git gc` runs and `Repository` has an instance to `Rugged::Repository`, a
bug in libgit2 may cause the instance to return a stale value or a missing
branch. This change not only optimizes the branch lookup so we don't have
to iterate through every branch, but it also works around the `git gc`
issue by forcing a repository reload every time `Repository#find_branch`
is called.

See: https://github.com/libgit2/libgit2/issues/1534

Closes #15392, #21470

Fixes #20456.

Closes #15552

Only visible when scrollable area is larger than height

- This would allow anyone with a personal access token (even a read-only
  token, once scopes are implemented) to escalate their access by
  obtaining the private token.