- we now use the hierarchy class also for epics
- also rename supports_nested_groups? into supports_nested_objects?
  - move it to a concern

Prefer `each` to `find` since the former does the same thing
except doesn't add the extra delegation step that may be causing
the binding_of_caller gem issues.

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/54281#note_119494004

Ruby 2.5.3 in combination with Rails 5 appears to crash in development
when a CI job is selected for a runner. For some reason, the return
inside the block seems to seg fault. Let's get rid of this since
this isn't a good coding practice in any case.

Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/54281

Also see https://bugs.ruby-lang.org/issues/15325.

The soft-archived builds cannot be run after some deadline time.
The intent is to aggressively recycle old builds after sometime.

This whitelists all existing offenses for the various CodeReuse cops, of
which most are triggered by the CodeReuse/ActiveRecord cop.

For directories application_settings --> labels.

Partially addresses #47424.

https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/71887977 was failing
due to confusion between Ci::Group and Group.
https://gitlab.com/gitlab-org/gitlab-ce/-/jobs/71887977

Per discussion in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9646#note_65730532 this logic is being optimized elsewhere and it will simplify things if we make less changes to this code right now.

don't differentiate between the different runner types, instead we rely
on the Runner model to provide the available projects.
scheduling is now applied to all runners equally.

This reverts the addition of the "goldiloader" Gem and all use of it.
While this Gem is very promising it's causing a variety of problems on
GitLab.com due to it eager-loading too much data in places where we
don't expect/can handle this. At least for the time being this means we
have to go back to manually fixing N+1 query problems, but at least
those should not cause a negative impact on availability.

This reverts merge request !17730