Mattermost fixes

See merge request !8654

correct the prometheus feature configuration according to https://gitlab.com/git…

See merge request !8703

correct the prometheus feature configuration according to https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template#L1147

Make cycle_analytics_events_spec.rb side-effect free

Closes #26622

See merge request !8594

Merge request widget class names update

See merge request !8700

[ci skip]

Replace merge request widget body

See merge request !8697

Add Prometheus docs

See merge request !8699

[ci skip]

Fixed bug with merge immediately button not working

See merge request !8696

[ci skip]

Replaces https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1237
Omnibus MR: https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests/1227
Omnibus issue: https://gitlab.com/gitlab-org/omnibus-gitlab/issues/1481

This was caused by using 'this' in a fat arrow function, so 'this' would not equal the jQuery element

Update autodeploy templates [ci skip]

See merge request !8695

Button by itself will submit forms. Button type button willn't

Closes #26999

See merge request !8694

Revert "Merge branch 'dont-persist-application-settings-in-test-env' into 'master'"

See merge request !8690

Introduced an offset limit to prevent the dropdown from going far right

Closes #26618 and #27023

See merge request !8679

This reverts merge request !8573

Fix Merge When Pipeline Succeeds immediate merge bug

Closes #26969

See merge request !8685

Filtered search input click back at token

See merge request !8617

Fix DropLab in IE11 v1 (merge edition)

Closes #26785

See merge request !8689

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/26785