switch issue and merge request to use it

Backport changes from gitlab-org/gitlab-ee!998

See merge request !8984

Fix filtered search user autocomplete for gitlab instances that are hosted on a subdirectory

Closes #27343

See merge request !8891

Remove lighter colored commit description border

See merge request !9005

Use vue.js Pipelines table in commit and merge request view

Closes #27141

See merge request !8844

Skip or retain project while deleting the project:

Closes #15005

See merge request !8960

Don't delete assigned MRs/issues when user is deleted

See merge request !8634

27240 Make progress bars consistent

Closes #27240

See merge request !8913

Fix markdown links in PROCESS.md

See merge request !8947

Fix References header parser for Microsoft Exchange

Closes #26567

See merge request !8620

Don't use backup AR connections for Sidekiq

Closes #27713

See merge request !9001

Issue filters in boards modal

Closes #26205

See merge request !8903

Remove coverage entry from global CI/CD options

See merge request !8981

Adding GitLab Pages to CE

Closes #14605, gitlab-com/infrastructure#1058, gitlab-ee#1333, and #323

See merge request !8463

Rename example from file_name to file_path

Closes #27643

See merge request !8959

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/8620#note_22868713

Add traits for ProjectFeatures to Project factory

Closes #24007

See merge request !8925

Update NFS HA doc with location -> config mapping

Closes #27685

See merge request !8993

Added specs for merge request environment list

See merge request !8937

Don't render snippet actions for logged-out users

Closes #27708

See merge request !8995

Resolve "Remove hover animation from row elements"

Closes #26863

See merge request !8842

V4 API: Remove deprecated MR and Issue endpoints and preserve V3 namespace

Closes #27180

See merge request !8967

Adding two extra connections does nothing other than increasing the
number of idle database connections. Given Sidekiq uses N threads it can
never use more than N AR connections at a time, thus we don't need more.

The initializer mentioned the Sidekiq upgrade guide stating this was
required.  This is false, the Sidekiq upgrade guide states this is
necessary for Redis and not ActiveRecord.

On GitLab.com this resulted in a reduction of about 80-100 PostgreSQL
connections.

Fixes #27713

# Conflicts:
#   db/schema.rb

Make all system notes lowercase

See merge request !8807

Modify the search bar area on admin/projects page

Closes #26794

See merge request !8776