Suggests to use a JSON structured log instead

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/54102

Rename ProjectEntity to IssuableEntity

Closes #58275

See merge request gitlab-org/gitlab-ce!30217

- Remove `FeatureConstrainer` call wrapping api endpoint
- Remove `Feature.enabled?(:graphql)` conditionals in back and frontend
- Modify graphql test to be graphql flag agnostic
- Remove api routing spec
- Remove frontend feature flag via `gon`

New API endpoint for merge request count
Updates all open tabs at the same time with one call
Restructured API response

API response changed to 401 if no current_user

Added API + JS specs

Fix for Static Check

Updated Count on Open/Close, Assign/Unassign of MR's

Checking if MR Count is refreshed

Added # frozen_string_literal: true to spec

Added Changelog

This MR introduces tracking of the `rebase_jid` for merge requests. As
with `merge_ongoing?`, `rebase_in_progress?` will now return true if a
rebase is proceeding in sidekiq.

After one release, we should remove the Gitaly-based lookup of rebases.
It is much better to track this kind of thing via the database.

Make Housekeeping button do a full garbage collection

Closes #63349

See merge request gitlab-org/gitlab-ce!30289