Based on !10841 Fix Error 500 when referencing issue with project in pending delete

Closes #31215

See merge request !10843

Refactor environments components into vue files - part 3

See merge request !10833

Fix user profile tabs showing raw json when navigating back and forward

See merge request !10352

Adding animation for all dropdown

Closes #26208

See merge request !8419

Add help regarding vue resource and where to include it

See merge request !10819

fix inline diff copying in firefox

Closes #31193

See merge request !10838

Refactor Admin::GroupsController#members_update method and add some specs

See merge request !10828

Add CHANGELOG entry

Mention Microsoft teams service in project services doc

See merge request !10815

Add doc for scheduled trigger

Closes #30440

See merge request !10591

Fix user activities API version in docs

[ci skip]

See merge request !10822

Fix encoding issue exporting a project

Closes #31186

See merge request !10824

Guarantee only one state is shown at a time

Closes #31189

See merge request !10835

Replace builds_enabled with jobs_enabled in projects API v4

Closes #31012

See merge request !10786

[ci skip]

Add Fork/Cancel confirmation to "Replace"/"Delete" buttons

Closes #30637

See merge request !10602

This is based on:

https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/10841

* upstream/master: (109 commits)
  Update CI templates to include 9.1 templates
  Change spec folder to match the assets one
  Update style_guide_js.md
  Milestones documentation refactor
  Adds documentation entry: Don't user forEach, aim for code without side effects
  Move kube namespace section to the variables one
  Changed milestone.to_reference calls into milestone.title for the show, edit and top views
  Update move icon to match others
  Issue Title Show Focus Check On Load
  Update Kubernetes namespace documentation
  Store projects in metrics for email replies
  Refactor into .vue files
  Adds vue js example application and documentation
  Add ES lint support to identify poorly written Promises
  Update plantuml.md to add the actual link.
  Fixed wording
  Add metrics events for incoming emails
  Remove helpers assigned_issuables_count and cached_assigned_issuables_count
  Refactor into .vue files part 2
  Fix headings
  ...

Change spec folder to match the assets one

See merge request !10834

Closes #31215

Update CI templates to include 9.1 templates

See merge request !10807

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30637

Add parameter limit to styleguide

See merge request !10830

Don't run the downtime check on stable branches, or tags/master

See merge request !10794

Kubernetes service namespace

Closes #30445

See merge request !10821

Milestones documentation refactor

See merge request !10812

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>