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.

Goldiloader is great, but has several issues with has_many :through relations:

* https://github.com/salsify/goldiloader/issues/12
* https://github.com/salsify/goldiloader/issues/14
* https://github.com/salsify/goldiloader/issues/18

Rather than try to figure out which applies in each case, we should just do the
drudge work of manually disabling autoloading for all relations of this type. We
can always use regular preloading for specific cases, but this way we avoid
generating invalid queries through Goldiloader's magic.

This reverts commit 54a575f1, reversing
changes made to c63af942.

Move uploads to object storage

Closes #4163

See merge request gitlab-org/gitlab-ee!3867

Comments from code review applied. Also switched forked_from_project and ForkedProjectLinks to ForkNetworkMember

The following optimizations were performed:

- Add new association to GroupMember and ProjectMember

  This new association will allow us to check if a user is a member of a
  Project or Group through a single query instead of two.

- Optimize retrieving of Members when adding multiple Users

parent_id is being set to 0 by RSpec.

Sub groups should not have a visibility level higher than its parent.

If the project is in a group, the `group.refresh_members_authorized_projects`
is made non-blocking, and we call `current_user.refresh_authorized_projects`
directly.

Projects in a personal namespace are more difficult. Rather than passing the
`blocking:` parameter through the entire `add_master` chain, have the
`AuthorizedProjectsWorker` automatically inline authorizations for three IDs or
less. Since the maximum number of IDs in this path is 2, that has the same effect.