Add use cases for issues-related EE features

Closes #2810

See merge request !2330

Add docs for Pivotal tile installation

See merge request !2341

Update Auditor users docs

See merge request !2333

See https://gitlab.com/gitlab-org/gitlab-ce/issues/34698#note_34276286
for the thorough explanation.
Signed-off-by: Rémy Coutable <remy@rymai.me>

[EE] Create and use project path helpers that only need a project, no namespace

See merge request !2336

[EE] Disable RSpec/BeforeAfterAll and enable RSpec/ImplicitExpect cops

See merge request !2305

Geo: Migrated checks to SystemChecks

See merge request !2331

[ci skip]

[ci skip]

Use trigger(:click) instead of trigger to avoid a weird transient bug

Closes #2843

See merge request !2340

Environment-specific variables

Closes #2302

See merge request !2112

Revert "Merge branch '18000-remember-me-for-oauth-login-ee' into 'master'"

See merge request !2345

Add a license check for group-webhooks

Closes #2576

See merge request !2280

This reverts merge request !2175

Fix spec failure for squash in progress error handling

See merge request !2343

Fixed admin sidebar not showing all options in new navigation

See merge request !2334

Port of 32838-admin-panel-spacing to EE

See merge request !2264

Show loading icon when retrieving Geo node status

Closes #1977

See merge request !2309

Resolve EE conflicts for "Fix API Scoping"

See merge request !2338

Similar to how we check project features.

- Hide the `webhooks` link from the group-settings page
- All group-webhooks-pages render a 404
- Don't execute webhooks if the feature is disabled

EE Port: Honor the "Remember me" parameter for OAuth-based login

See merge request !2175

Signed-off-by: Rémy Coutable <remy@rymai.me>

* ee/master: (25 commits)
  Introduce namespace license checks for Push Rules (EES)
  Use a named subject in `models/ee/board_spec.rb`
  Hide the milestone variable on board when the feature is disabled
  Hide the milestone in the API when the feature is not available
  Don't update milestones on boards if the feature is not available
  Hide editing/creating milestones from the board UI
  Add `issue_board_milestone` feature to license
  Split Projects:Settings::RepositoryController into CE and EE sections
  Refactor Projects::CreateService and specs to make EE-only code clearer
  Fix EE conflicts for "Allow unauthenticated access to the `/api/v4/users` API"
  Introduce namespace license checks for merge request approvers (EES)
  Remove an unnecessary "included do ... end" block in app/models/concerns/approvable.rb
  Raise an error if an unknown feature is passed to stub_licensed_features
  Don't show Issue/MR template Setting if feature not available
  Only set MR description from template when feature available
  Only set issues template from setting if feature available
  Add Issuable Default Template feature to License
  Update CHANGELOG.md for 9.3.4
  Update CHANGELOG-EE.md for 9.3.4-ee
  Hide `Focus mode` on issue boards
  ...