Upgrade Prometheus to 2.4.3 and Alertmanager to 0.15.2

Hotfix for Rspec and second storage

See merge request gitlab-org/gitlab-ce!22558

Bump google-protobuf to 3.6.1

See merge request gitlab-org/gitlab-ce!22559

Rails requires a second storage for testing cross shard features. Gitaly
will not boot if this second storage doesn't exist. So this will create
this storage without adding it to the list of storages that Rails knows
about.

It looks like gRPC may have worked around
https://github.com/google/protobuf/issues/4210 via
https://github.com/grpc/grpc/pull/14634.

This is needed to support Ruby 2.5
(https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22555).

Sync group sidebar template with EE

See merge request gitlab-org/gitlab-ce!22549

Resolve "Endless scroll loader is visible on user profile overview page"

Closes #53023

See merge request gitlab-org/gitlab-ce!22529

Fix link in doc/user/project/repository/branches/index.md

See merge request gitlab-org/gitlab-ce!22554

doc: Fix broken link hrefs for ee and gitlab-versions

See merge request gitlab-org/gitlab-ce!22540

Add instructions on how to enable a feature flag

Closes gitlab-org/release/framework#23

See merge request gitlab-org/gitlab-ce!22518

Correcting a typo

See merge request gitlab-org/gitlab-ce!22511

Administrator documentation for Pages access control

See merge request gitlab-org/gitlab-ce!22146

- Allow to extend nav links for the Group sidebar

Removes duplicate escape from job item

Closes #53013

See merge request gitlab-org/gitlab-ce!22536

Fix ee-compat-check by not modifying frozen strings

Closes #53030

See merge request gitlab-org/gitlab-ce!22527

Add review app

Closes #52188 and #49569

See merge request gitlab-org/gitlab-ce!22010

Update dev security workflow template

See merge request gitlab-org/gitlab-ce!22532

Signed-off-by: Rémy Coutable <remy@rymai.me>

* Use 2 space indentation in review-apps.sh script
* Move automated_review_cleanup back to build stage

* Uses the same supporting code as used in EE
* Includes automated cleanup
* Install external-dns helm chart to review apps cluster if it isn't
already
* Adds variables REVIEW_APPS_AWS_SECRET_KEY and
REVIEW_APPS_AWS_ACCESS_key
* review-apps-ce uses a different cipher

Improve review apps

Closes #6875

See merge request gitlab-org/gitlab-ee!6665

[ci skip]

Tooltips aren't using v-html anymore thus causing
escape not to be needed

Update Runner Chart to 0.1.35

See merge request gitlab-org/gitlab-ce!22541

Add dbname to MySQL migration GRANT command

See merge request gitlab-org/gitlab-ce!21719

Support licenses and performance

See merge request gitlab-org/gitlab-ce!22175

Update Todo icons in collapsed sidebar for Issues and MRs

See merge request gitlab-org/gitlab-ce!22534

Alias the lfs_enabled method

Closes #49348

See merge request gitlab-org/gitlab-ce!22501

Add RoleBinding method and class

See merge request gitlab-org/gitlab-ce!22524

Remove broken git storage for testing

See merge request gitlab-org/gitlab-ce!22530

Add `Any` option to milestone filter

See merge request gitlab-org/gitlab-ce!22351