This removes erroneously defined polymorphic association, because
specifying `belongs_to` relationship with a class that already supports
polymorphic associations works out-of-the-box.

We share metadata attributes between processable `Ci::Build` and
`Ci::Bridge`. Common implementation can be extracted to a concern to
make it easier to share it, and to build abstraction for attributes that
are stored in a separate table as a metadata.

It is now possible to pass variables to a downstream pipeline from a
bridge job. Variables defined as YAML variables for this bridge job are
going to be populated downstream, and are going to be available in every
job created within a downstream pipeline. These variables are then going
to be passed to GitLab Runner as environment variables.

Bump Sidekiq to 5.2.5

See merge request gitlab-org/gitlab-ce!24662

Feature switch layer around Approvable and VisibleApprovable

See merge request gitlab-org/gitlab-ee!9147

Adds new and edit modules FF store

See merge request gitlab-org/gitlab-ee!9292

Fix `star` action in the `explore` subpages

See merge request gitlab-org/gitlab-ce!24693

[Part 3] Add support for start and due dates in Epic sidebar

See merge request gitlab-org/gitlab-ee!9304

To eager load rules, reuse the association without scope.
Filter those rules using `regular?` method.

as it is no longer needed.

Apply project scope

It is now wished for the feature to be disabled by default.
Since we can't control when the background migration finishes,
which would set the old flag to true,
changing the flag is easier to work around with.

From dev.gitlab repo

DRY maintainer

The logics are copied over but unchanged.

Similar to MergeRequestPresenter

Logic unchanged

Only call ApprovalState when enabled

Add query method for id

See merge request gitlab-org/gitlab-ce!24386

Standardize token value capitalization in filter bar

Closes #54213

See merge request gitlab-org/gitlab-ce!23846

Adds start and due date pickers within sidebar.
Supports for expand and collapsed sidebar states.

Fix create_edit_delete_epic_spec.rb test flakiness

Closes gitlab-org/quality/nightly#63

See merge request gitlab-org/gitlab-ee!9300

This reduces duplication caused by gitlab-monitor already shipping
Sidekiq 5.2.5. The only changes appear to be minor:

https://github.com/mperham/sidekiq/blob/master/Changes.md