Copyedit pipelines-related documentation

Closes #59006

See merge request gitlab-org/gitlab-ce!26198

Refactor new content for stage keyword

See merge request gitlab-org/gitlab-ce!25953

Add registry to dev arch docs

See merge request gitlab-org/gitlab-ce!25951

Add registry to dev arch docs

See merge request gitlab-org/gitlab-ce!25951

Merge branch '47491-gitlab-fakeapplicationsettings-doesn-t-respond-to-all-the-methods-applicationsetting-responds-to-itself' into 'master'

Introduce ApplicationSettingImplementation

Closes #47491

See merge request gitlab-org/gitlab-ce!25803

Add artillery.io load testing script and rake tasks

See merge request gitlab-org/gitlab-ce!26210

Also add rake tasks that makes use of existing performance data
genertion task.

So the fake can enjoy it, too. We don't use `prepend`
because that'll require we change `allow_any_instance_of` to
`expect_next_instance_of`, but that's not very easy to do.
We can do that later.

Fix undefined variable error on json project views

See merge request gitlab-org/gitlab-ce!26297

This mistake seems to have always been there, but it only resulted in
errors on the `/explore*.json` since they were the one that _actually_
relied on the local variables.

Fix spec for routes to the GraphqlController

See merge request gitlab-org/gitlab-ce!26231

Implement suggestion diff lines parser

See merge request gitlab-org/gitlab-ce!26069

Fix test-plan label in the template

See merge request gitlab-org/gitlab-ce!26283

Fixed backup of non default upload directory

See merge request gitlab-org/gitlab-ce!25736

Replaced Settings with Gitlab.config for uniformity

Updating nginx_status link in index.md to use the proper anchor to nginx.html

See merge request gitlab-org/gitlab-ce!26245

Use the same standard for method names on project activity and menu page objects

See merge request gitlab-org/gitlab-ce!24738

... page objects.

Also, update the affected test case.

I choose `click_...` instead of `go_to_...` since it describes
better what the method really does, which is clicking on something.

I know there are other places in the code where methods start with
`click_` and others where methods start with `go_to_`, with that
I'd like to start a discussion or be pointed to the right issue if
there is already one so that we can address this in the whole
framework.
This contribution could be the start in the direction of using the
standard chosen here.

Move EE specific code out of lib/gitlab

See merge request gitlab-org/gitlab-ce!25741

Removes EE differences for clusters/_sidebar.html.haml

Closes gitlab-ee#10428

See merge request gitlab-org/gitlab-ce!26271

Resolve "Spinners are active prematurely in Bitbucket Cloud import"

Closes #58889

See merge request gitlab-org/gitlab-ce!26175

Fix storage migration check for non-empty queues

Closes #58739

See merge request gitlab-org/gitlab-ce!26109

Fix skipping of user rendering for none and any

See merge request gitlab-org/gitlab-ce!26268

Resolve "Z-Index Issue on Pipeline Dropdown"

Closes #58999

See merge request gitlab-org/gitlab-ce!26274

Merge branch 'ce-10421-implement-the-retrieval-reading-of-the-insights-file-to-be-used-in-the-insights-controller' into 'master'

New Repository#insights_config method

Closes gitlab-ee#10421

See merge request gitlab-org/gitlab-ce!26183

This backports the changes EE made to Gitlab::UserExtractor, removing
the need for an EE specific module.

Update acts-as-taggable-on 5.0 -> 6.0

See merge request gitlab-org/gitlab-ce!26051

This commit lowers the z-index of the .merge-request-tabs-holder class
to avoid rendering conflicts with the mini pipeline status dropdown
on the merge request page.

Removes EE differences for pipelines/index.html

Closes gitlab-ee#6353

See merge request gitlab-org/gitlab-ce!26226