Merge branch '26165-combine-runners-and-variables-and-triggers-and-ci-cd-pipelines-settings-pages' into 'master'

Merge Triggers, Runners, Variables and Pipelines to a single option called "CI/CD Pipelines"

Closes #26165

See merge request !8430

add the stewardship label to contributing.md

See merge request !8997

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

Also updated the #update action inside the variables controller as
to render the show and not redirect back to the settings route

Redirections now show a flash message wether the variable was created correctly or not using a flash message

Added tests to verify the access policy to the new controller

Added test for the CiCdPipelinesController

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