Backport of EE "catch entering username as an email instead of returning a 500 error"

See merge request gitlab-org/gitlab-ce!21085

Add Bitbucket Server importer docs

See merge request gitlab-org/gitlab-ce!21097

Update doc/integration/oauth_provider.md

See merge request gitlab-org/gitlab-ce!21093

Docs: fix ee-conflict in bulk editing

See merge request gitlab-org/gitlab-ce!21091

Add details for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20164.

Merge branch 'rd-fix-bug-when-authenticating-user-for-repo-with-size-check-enabled-ce' into 'master'

Backport of gitlab-org/gitlab-ee!6848

See merge request gitlab-org/gitlab-ce!21096

Fix Bitbucket Cloud importer omitting replies

Closes #50052

See merge request gitlab-org/gitlab-ce!21076

Remove redundant ci_builds (status) index

See merge request gitlab-org/gitlab-ce!21070

Enable more frozen string in app/models/**/*.rb

See merge request gitlab-org/gitlab-ce!21019

Keep project repository settings sections expanded after submitting form

See merge request gitlab-org/gitlab-ce!21082

Keep project settings sections expanded after submitting form

See merge request gitlab-org/gitlab-ce!21079

Keep group settings sections expanded after submitting form

See merge request gitlab-org/gitlab-ce!21083

CE port of "Add date fields to Epic to enable dates to source from milestones"

See merge request gitlab-org/gitlab-ce!20687

Update CONTRIBUTING.md

See merge request gitlab-org/gitlab-ce!21075

Update licenses and templates

See merge request gitlab-org/gitlab-ce!21084

Fix broken text in OAuth authorization screen

See merge request gitlab-org/gitlab-ce!21080

Porting MR Vue Memory Fixes to current master

See merge request gitlab-org/gitlab-ce!21028

Resolve "Group dashboard > Line height is too tall for group names"

Closes #46703 and #50064

See merge request gitlab-org/gitlab-ce!21033

Keep project CI/CD settings sections expanded after submitting form

See merge request gitlab-org/gitlab-ce!21077

Inline diff comments did not have the proper position, so even though
they had line codes the merge request validation would fail. Now
we cache the line position for each parent comment and use that.

Closes #50052

Don't set gon variables in JSON requests

See merge request gitlab-org/gitlab-ce!21016