Migrate Repository#find_commits_by_message to Gitaly

Closes gitaly#443

See merge request !13268

Migrate Gitlab::Git::Repository#size to Gitaly

Closes gitaly#437

See merge request !13259

Issuables: Move some code from create services to Sidekiq workers

See merge request !13326

DeclarativePolicy: reduce iterations of the step set

See merge request !13352

Add two more metrics for CI/CD

See merge request !13039

Remove JS flicker on page load; UI tweaks

See merge request !13347

Group-level new issue & MR using previously selected project

Closes #34411

See merge request !13058

Store & use ConvDev percentages returned by Version app

Closes #35761

See merge request !13217

[EE Backport] Update log audit event in omniauth_callbacks_controller.rb

See merge request !13339

Backport changes in https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2551 to CE

Closes #21391

See merge request !13275

Add Gitlab::Git::Blob.batch method

See merge request !13225

Improve mobile sidebar

Closes #35483

See merge request !13349

rather than iterating the whole remaining step set with
.all?(&:prevent?)

Resolve "Remove jQuery Nicescroll"

Closes #15664, #30860, and #35885

See merge request !13262

Upgrade to webpack v3.4.0

Closes #33902

See merge request !12298

Improve GitHub importer

Closes #27429

See merge request !12886

Allow projects to be started from a template

Closes #32420

See merge request !13108

Support group milestone references

Closes #34778

See merge request !13289

Set default options outside the raw_log method

See merge request !13346

Reset only migration models

Closes #36052

See merge request !13336

We had a lot of copied and pasted code, when the different elements were very
small and easy to get wrong.

Removes test for removed behavior

Add sidekiq metrics endpoint and add http server to sidekiq

See merge request !13082