Merge remote-tracking branch 'upstream/master' into gem/sm/bump-google-api-client-gem-from-0-8-6-to-0-13-6

* upstream/master: (130 commits)
  Handle error when fetching ref for MR with deleted source branch
  refactor emails service
  fix update service
  refactor users update service
  refactor keys controller
  refactor some controllers to make them EE friendly
  fix specs
  fix users update service
  update initializers
  refactor services to match EE signature
  Change recommended MySQL version to 5.6
  Clarify artifact download via the API only accepts branch or tag name for ref
  Clean merge_jid whenever necessary on the merge process
  Rolling back change to n+1 detection
  Breadcrumbs receives padding when double lined
  karma spec fixes
  Add EEP to headings
  Added some Gitaly docs to `docs/development`
  Check orientation of profile image
  Fixed missing namespaces on navigation translations
  ...

Resolve "NoMethodError: undefined method `sha' for nil:NilClass"

Closes #38319

See merge request gitlab-org/gitlab-ce!14547

Clarify artifact download via the API only accepts branch or tag name for ref

See merge request gitlab-org/gitlab-ce!14545

Fixed missing namespaces on navigation translations

See merge request gitlab-org/gitlab-ce!14472

Lazy load images in mobile sidebar & header

Closes #38276

See merge request gitlab-org/gitlab-ce!14526

Fixes commit comments in parallel diff view

Closes #38117

See merge request gitlab-org/gitlab-ce!14529

If the ref doesn't exist, and the source branch is deleted, we can't get it back
easily. Previously, we ignored this error by shelling out, so replicate that
behaviour.

RepositoryExists is always called with #gitaly_migration

Closes #38333

See merge request gitlab-org/gitlab-ce!14513

Refactor services to match EE signature

See merge request gitlab-org/gitlab-ce!14385

Clean merge_jid whenever necessary on the merge process

Closes #38476

See merge request gitlab-org/gitlab-ce!14540

Check orientation of profile image

See merge request gitlab-org/gitlab-ce!14461

Change recommended MySQL version to 5.6

Closes #38152

See merge request gitlab-org/gitlab-ce!14546

Cleanup diff-notes-collapse css

See merge request gitlab-org/gitlab-ce!14515

MergeRequest#merge_jid should be cleaned up whenever we hit a known error on MergeService#execute. This way we can keep track if the MR is really "ongoing" or "stuck"

Rolling back change to n+1 detection

See merge request gitlab-org/gitlab-ce!14536

Add things that the k8s integration enables

Closes #37529

See merge request gitlab-org/gitlab-ce!14163

Fix linting errors in locale/index.js

See merge request gitlab-org/gitlab-ce!14521

RepoEditor: Implement line and range linking.

Closes #38254

See merge request gitlab-org/gitlab-ce!14448

Breadcrumbs receives padding when double lined

See merge request gitlab-org/gitlab-ce!14298

Added some Gitaly docs to `docs/development`

[ci skip]

See merge request gitlab-org/gitlab-ce!14473