Migrate merge base, merged branches, write ref

Closes gitaly#748, gitaly#695, and gitaly#799

See merge request gitlab-org/gitlab-ce!20639

Add emails delivery metrics

Closes #49214

See merge request gitlab-org/gitlab-ce!20638

Resolve "Change API docs to reflect that lookup by username does not require admin access"

Closes #38095

See merge request gitlab-org/gitlab-ce!20646

Update pipelines.md to have correct curl commands

See merge request gitlab-org/gitlab-ce!20653

Fix archived parameter for projects API

Closes #32301

See merge request gitlab-org/gitlab-ce!20566

Fix typo in CSS transform property for Memory Graph component

Closes #49291

See merge request gitlab-org/gitlab-ce!20650

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

Closes #49061

See merge request gitlab-org/gitlab-ce!20615

Enable frozen string in apps/services/*.rb

See merge request gitlab-org/gitlab-ce!20401

Update issue closing pattern

Closes #49166

See merge request gitlab-org/gitlab-ce!20554

Update Git version to 2.18.0

See merge request gitlab-org/gitlab-ce!20489

Fix invalid link to GitLab.com architecture.md

See merge request gitlab-org/gitlab-ce!20645

Add a 10 ms bucket for SQL timings

See merge request gitlab-org/gitlab-ce!20527

i18n: externalize strings from 'app/views/import'

See merge request gitlab-org/gitlab-ce!19732

Partially addresses #47424.

Move "search by email or username" block to "for normal users" section

Signed-off-by: Tao Wang <twang2218@gmail.com>

Update 10.6-to-10.7.md

See merge request gitlab-org/gitlab-ce!20610

Remove Repository#lookup and unreachable rugged code

See merge request gitlab-org/gitlab-ce!20553

Merge branch '48745-project-exports-fail-when-uploads-have-been-migrated-to-object-storage' into 'master'

Resolve "Project exports fail when uploads have been migrated to object storage"

Closes #48745

See merge request gitlab-org/gitlab-ce!20484

Make it more explicit what environment stop actions are

Closes #48672

See merge request gitlab-org/gitlab-ce!20587

i18n: externalize strings from 'app/views/doorkeeper'

See merge request gitlab-org/gitlab-ce!19695

Add the CI Job trigger as the build trigger

Closes charts/gitlab#586

See merge request gitlab-org/gitlab-ce!20619

QA: Remove flaky and redundant expectations

Closes #49164

See merge request gitlab-org/gitlab-ce!20616

Trigger rails5 tests if variable is set

See merge request gitlab-org/gitlab-ce!20609

Allow Danger step to fail

See merge request gitlab-org/gitlab-ce!20624

Fix Danger checks for invalid Changelogs

See merge request gitlab-org/gitlab-ce!20603

Resolve "Auto DevOps help page - link has moved"

Closes #49262

See merge request gitlab-org/gitlab-ce!20632