Update CI to test with Ruby v2.6.6

See merge request gitlab-org/gitlab!30909

Part of https://gitlab.com/gitlab-org/gitlab/-/issues/198579

Remove metrics_dashboard_visibility_switching_available feature flag

See merge request gitlab-org/gitlab!29718

Move Milestone methods to Timebox

See merge request gitlab-org/gitlab!30128

Introduce `skip_live_env` RSpec meta and add it to tests

Closes gitlab-org/quality/team-tasks#493

See merge request gitlab-org/gitlab!30661

Add check for new email addition in audit test

Closes #207741

See merge request gitlab-org/gitlab!30679

Gitlab/Json cop autocorrects in /lib

See merge request gitlab-org/gitlab!30627

Dequarantine Burndown chart spec

See merge request gitlab-org/gitlab!30871

Add import/export information to dev docs

See merge request gitlab-org/gitlab!29820

Move all methods Milestone and Sprint will share to Timebox

Dequarantine create snippet spec

Closes #215031

See merge request gitlab-org/gitlab!30862

Spec passed on staging

Improve Jenkins integration docs

See merge request gitlab-org/gitlab!30577

Fix markdown preview styling for dark theme

See merge request gitlab-org/gitlab!30477

Added json index action to cluster controller

Closes #207031

See merge request gitlab-org/gitlab!30635

Multiple metrics edit navigates to prom edit page

See merge request gitlab-org/gitlab!30666

Log Puma timeouts for API calls

See merge request gitlab-org/gitlab!30885

Adds the detailed alert skeleton for alert management

See merge request gitlab-org/gitlab!30804

* Adds mock data

Merge branch '215616-geo-synchronisation-status-is-empty-when-nothing-is-synchronised' into 'master'

Geo: Fix empty synchronisation status when nothing is synchronised

Closes #215616

See merge request gitlab-org/gitlab!30710

Apply suggestion to ee/changelogs/unreleased/215616-geo-synchronisation-status-is-empty-when-nothing-is-synchronised.yml

Migrate time ago spec to jest

See merge request gitlab-org/gitlab!30875

This handles a specific exception raised
by `rack-timeout` Gem when Puma requests
surpass the configured timeout.

This exception wasn't being handled properly
(and logged), given it inherits from `Exception`,
which is not handled by Grape `rescue_from :all`.

Add new json response to cluster index action
Add new serializer fields to display json content
Added tests for new controller

Resolve "Document how to switch authorised account for BitBucket import"

See merge request gitlab-org/gitlab!30856

Migrated time ago karma spec
to jest and now using vue test
utils.

Update managed jupyter chart to 0.9.0 (stable)

See merge request gitlab-org/gitlab!30393

Use correct label for Number of tags to retain

See merge request gitlab-org/gitlab!30858

Add method for sectional processing of CODEOWNERS

See merge request gitlab-org/gitlab!30529

Spec is not failing after the fix

Gitlab/Json cop autocorrects in /app, /spec

See merge request gitlab-org/gitlab!30624