Merge branch 'blackst0ne-rails5-activerecord-statementinvalid-mysql2-error-expression-1-of-select-list-is-not-in-group-by-clause' into 'master'

[Rails5] Fix milestone GROUP BY query

Closes #48428

See merge request gitlab-org/gitlab-ce!20256

Extract EE-specific lines from NotificationService

See merge request gitlab-org/gitlab-ce!20406

Allow to store BuildTraceChunks on Object Storage

Closes #45712

See merge request gitlab-org/gitlab-ce!19515

Partially revert "Revert "Merge branch 'gitaly-mandatory-20180703-jv' into 'master'""

See merge request gitlab-org/gitlab-ce!20422

Backport of EE changes "Add support for autocompleting Epics and Labels within Epics"

See merge request gitlab-org/gitlab-ce!20419

Added merge request info to Web IDE sidebar

Closes #45187

See merge request gitlab-org/gitlab-ce!19860

Resolve "Undefined omniauth_authorize_path when omniauth_enabled not enabled"

Closes #48677

See merge request gitlab-org/gitlab-ce!20302

Create cross project group features

See merge request gitlab-org/gitlab-ce!20333

This partially reverts commit 64dfe2cb.

Fix cross-project label references

Closes #45539

See merge request gitlab-org/gitlab-ce!20308

Remove redundant query when removing trace

See merge request gitlab-org/gitlab-ce!20324

Refactor AutocompleteSources#label:

1. The return value was inconsistent, sometimes returning a hash and sometimes returning an ActiveModel.
2. It was inconsistent with respect to other methods in the class since they all return ActiveModels.

Check if the existences of archived traces before archive it

Closes #48705

See merge request gitlab-org/gitlab-ce!20297

CE for "Remove new contributing link from EE"

See merge request gitlab-org/gitlab-ce!20334

Fix User role displayed on projects dashboard

Closes #43565

See merge request gitlab-org/gitlab-ce!20374

This allows us to check specific abilities in views, while still
enabling/disabling them at once.

Resolve "GFM preview should have status indicator"

Closes #31583

See merge request gitlab-org/gitlab-ce!20418

Resolve "MRs are showing some discussions as unresolved"

Closes #48803

See merge request gitlab-org/gitlab-ce!20351

Add "Why GitLab?" page to GitLab CE README

See merge request gitlab-org/gitlab-ce!20415

CE: Unify app/views/shared/issuable/_search_bar.html.haml

See merge request gitlab-org/gitlab-ce!20266

Merge branch '48893-getting-undefined-local-variable-or-method-page-for-errors-in-qa-jobs' into 'master'

Resolve "Getting "undefined local variable or method `page' for" errors in QA jobs"

Closes #48893

See merge request gitlab-org/gitlab-ce!20410