Resolve "MR refactor: All actions under diff module are being exported twice"

Closes #48951

See merge request gitlab-org/gitlab-ce!20499

Fix link to frontend in handbook

See merge request gitlab-org/gitlab-ce!20504

Shorten CHANGELOG filename to avoid breaking ecryptfs users

Closes #49038

See merge request gitlab-org/gitlab-ce!20512

[ci skip]

Closes #49038

Replace 48976-rails5-invalid-single-table-inheritance-type-group-is-not-a-subclass-of-gitlab-backgroundmigration-fixcrossprojectlabellinks-namespace.yml

Add additional headline for Adding SSH keys to GitLab

Closes #46395

See merge request gitlab-org/gitlab-ce!20507

Document that we don't want to wait in tests

See merge request gitlab-org/gitlab-ce!20502

Preserve the correct start/due dates on milestones when editing

Closes #41671

See merge request gitlab-org/gitlab-ce!20279

Remove badges from README.md in favor of GitLab badges feature

Closes #48895

See merge request gitlab-org/gitlab-ce!20447

Request to be a proofreader.

See merge request gitlab-org/gitlab-ce!19423

Rails5 mysql fix milliseconds problem in pull request importer spec

See merge request gitlab-org/gitlab-ce!20475

Use Gitaly's OperationService.UserUpdateBranch RPC

Closes gitaly#1252

See merge request gitlab-org/gitlab-ce!20231

Use the correct script location for the build trigger script

See merge request gitlab-org/gitlab-ce!20454

Update hamlit to fix ruby 2.5 incompatibilities, fixes #42045

Closes #42045

See merge request gitlab-org/gitlab-ce!20315

Fix search bar text input alignment

Closes #48288

See merge request gitlab-org/gitlab-ce!20155

Rails5 fix mysql milliseconds problem in specs

Closes #48977

See merge request gitlab-org/gitlab-ce!20464

Update Gemfile.rails5.lock with latest Gemfile.lock changes

See merge request gitlab-org/gitlab-ce!20466

Resolve "Markdown help incorrect in how wiki pages are rendered"

Closes #48970

See merge request gitlab-org/gitlab-ce!20459

Docs: make it clear that you need a completely separate domain for Pages

Closes #31961

See merge request gitlab-org/gitlab-ce!20369

Add FileUploader.root to allowed upload paths

Closes gitlab-qa#291

See merge request gitlab-org/gitlab-ce!20472

Show "Sign in" instead of "Sign in / Register" when sign up is disabled

See merge request gitlab-org/gitlab-ce!20474

Removes double export for actions in diffs module in mr refactor

Fix handling of annotated tags when Gitaly is not in use

Closes #47797

See merge request gitlab-org/gitlab-ce!20497

Resolve "Use namespaped module for diffs"

Closes #48960

See merge request gitlab-org/gitlab-ce!20442

Attempting to view an annotated tag in the TreeController would result
in `NoMethodError: undefined method 'tree'` when Rugged was in use.
`Blob#find_by_rugged` assumes that the ref is a true. Using
the commit ID ensures that the right ref is being used.

Note that in 11.1, `Blob#find` no longer uses Rugged, so this is only
a bug in 11.0.

Closes gitlab-org/gitlab-ce#47797