Add specs for new parameter and updated documentation as well.

Eliminate Gitaly N+1 queries with notes API

See merge request gitlab-org/gitlab-ce!32089

Increase sort options for issues list from updated_at and create_at,
to include more options close to what is required in actual issue list
UI.

This helps us to use REST API for issues list with sorting capabilities

https://gitlab.com/gitlab-org/gitlab-ce/issues/57402

Similar to https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31834,
we see that in https://gitlab.com/gitlab-org/gitlab-ce/issues/65957
there can be hundreds, even thousands, of Gitaly requests in the
`/api/:version/projects/:id/merge_requests/:noteable_id/notes` endpoint.

Previously, the API to retrieve notes generated hundreds of Gitaly calls
to determine whether a system note should be shown to the user. It did
this by:

1. Rendering the Markdown
2. Extracting cross-references from the Markdown
3. Issuing a Gitaly `FindCommit` RPC for every reference to validate
that the commit exists.

The last step is unnecessary because we don't need to display a commit
if the user doesn't have access to the project in the first place.
`RendersNotes#prepare_notes_for_rendering` is already used in
`MergeRequestsController`, which is why we don't see N+1 Gitaly calls
there. We use it here to optimize the note redaction process.

Remove KubernetesService integration

See merge request gitlab-org/gitlab-ce!31365

Remove label issue and MR counts from default API responses

See merge request gitlab-org/gitlab-ce!31543

As decided in https://gitlab.com/gitlab-org/gitlab-ce/issues/53593

These counts significantly increase the load time for these
requests. Users can now opt in to receiving the counts by setting
`with_counts=true` in requests. This is a breaking change, but hopefully
a fairly minor one.

Creating new records has been disabled, and all
existing records been migrated to clusters as of
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28534