[EE] Add discussion API

See merge request gitlab-org/gitlab-ee!4821

* adds basic discussions API for issues, snippets and epics
* adds notes API endpoint to epics
* reorganizes notes specs (so same tests can be used for all noteable types - issues, MRs, snippets, epics)

Unify deployment_platform interface with CE

See merge request gitlab-org/gitlab-ee!4875

Make sure we override the method from CE, too

Make --prune a configurable parameter in fetching a git remote

See merge request gitlab-org/gitlab-ee!4818

Improve "Bring a demoted primary back online" documentation

Closes #4934

See merge request gitlab-org/gitlab-ee!4578

Remove duplicate code

See merge request gitlab-org/gitlab-ee!4871

[EE] Speedup rake jobs

See merge request gitlab-org/gitlab-ee!4857

This was added in !4860, but somehow the code was was already present in
9c000451, causing https://gitlab.com/gitlab-org/gitlab-ee/-/jobs/56081024
to fail.

EE Port of "Remove common_vue bundle"

See merge request gitlab-org/gitlab-ee!4849

Port of ee-183-common-code-backport to EE

See merge request gitlab-org/gitlab-ee!4860

Projects and MRs Approvers API

Closes #183

See merge request gitlab-org/gitlab-ee!4636

CE upstream - 2018-03-06 15:24 UTC

Closes gitaly#1056, gitaly#1059, and gitlab-com/gitlab-docs#154

See merge request gitlab-org/gitlab-ee!4858

Fixes and enhancements for Geo admin dashboard

Closes #4658, #4864, and #4493

See merge request gitlab-org/gitlab-ee!4536

Add labels support to Epics

Closes #3727 and #4032

See merge request gitlab-org/gitlab-ee!4773

allow changing of approval related configuration as well as adding and
removing approvers and approver groups for both Projects and MRs

Resolve "Repository mirroring should notify when failed"

Closes #1123

See merge request gitlab-org/gitlab-ee!4699

Port to EE "Add archive feature to trace"

See merge request gitlab-org/gitlab-ee!4776

This should speed up a bit some jobs.

Also, use ruby:2.4-alpine image in the flaky-examples-check job
Signed-off-by: Rémy Coutable <remy@rymai.me>

EE PORT Bring one group issue board to CE

See merge request gitlab-org/gitlab-ee!4606

Unify lib/api/merge_requests.rb between CE and EE

See merge request gitlab-org/gitlab-ee!4404