`#referenced_merge_requests` preloaded too many associations. Award emoji, for
instance, are completely unnecessary here.

`#closed_by_merge_requests` had the opposite problem: `#all_references` needs
each item's author, and these weren't preloaded.

These methods don't really need to be on the Issue model. Issue#related_branches
can also be moved to a service, but we can do that in a separate commit.

This commit does not change any behaviour; it just moves code around, renames
the service, and refactors the specs.

Fixed deleting new files creating wrong state in IDE

Closes #50255

See merge request gitlab-org/gitlab-ce!21225

Added missing html_safe on text messages.

See merge request gitlab-org/gitlab-ce!21232

Enable frozen in app/mailers/**/*.rb

See merge request gitlab-org/gitlab-ce!21147

Add Acceptance testing issue template

See merge request gitlab-org/gitlab-ce!21156

Core backports from the Premium license templates feature

See merge request gitlab-org/gitlab-ce!21212

Duplicate specs testing emoji awards on issues

Closes #45238

See merge request gitlab-org/gitlab-ce!21126

Closes #50255

Add author-link style from common.scss in EE

See merge request gitlab-org/gitlab-ce!21204

Reduce number of model instances needed in test.

Closes #49788

See merge request gitlab-org/gitlab-ce!21192

Add Czech as an available language

Closes #43227

See merge request gitlab-org/gitlab-ce!21201

Documentation for JUnit XML Test Summary In MR widget

Closes #49867

See merge request gitlab-org/gitlab-ce!21061

Port EE changes for mirrors/_instructions.html.haml

See merge request gitlab-org/gitlab-ce!21107

Add a "user_show_add_ssh_key_message" application setting for use with SSH certificates

Closes #49953

See merge request gitlab-org/gitlab-ce!21027

New translations added to `locale/cs_CZ` will automatically be picked up.

Closes #49788.

Backport of https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6860

See merge request gitlab-org/gitlab-ce!21200

Creates vue component for artifacts block

See merge request gitlab-org/gitlab-ce!21198

chore(docs): add field repository_update_events

See merge request gitlab-org/gitlab-ce!21205

Fix `bin/secpick` rainbow gem error, and security branch prefixing

See merge request gitlab-org/gitlab-ce!21210

Resolve "JS Pages do not load on windows 8, IE 11"

Closes #50281

See merge request gitlab-org/gitlab-ce!21214

Vendor in Auto-DevOps.gitlab-ci.yml to update glibc to 2.28

Closes #50294

See merge request gitlab-org/gitlab-ce!21191

MR Page incremental rendering

See merge request gitlab-org/gitlab-ce!21063

Modified find project method to return nil if project not found

See merge request gitlab-org/gitlab-ce!21168

Resolve "Clicking on the text of checkboxes of runner's settings should toggle the checkbox"

Closes #49905

See merge request gitlab-org/gitlab-ce!21165