Docs first iteration: getting started subscriptions

Closes gitlab-ce#56876, gitlab-ce#56875, and gitlab-com/support/support-team-meta#1323

See merge request gitlab-org/gitlab-ee!9938

Repository indexing gaps handling

Closes #10712

See merge request gitlab-org/gitlab-ee!10273

Mention that deploy tokens and user/passwd don't work for Maven

See merge request gitlab-org/gitlab-ee!10475

Docs: Fix anchor to deprecated variables doc

See merge request gitlab-org/gitlab-ce!26788

Refactor and restructure environments page

See merge request gitlab-org/gitlab-ce!26400

Port from CE: Refactor and restructure environments page

See merge request gitlab-org/gitlab-ee!10335

- Groups content into relevant sections.
- Content edited.

Refactor and fix pipeline schedules

See merge request gitlab-org/gitlab-ce!26756

Allow streaming io objects into Gitaly

See merge request gitlab-org/gitlab-ce!26738

Fail Jest tests for unhandled Promise rejections

Closes #56053

See merge request gitlab-org/gitlab-ce!26424

Fail for unhandled Promise rejections in Jest (EE-port)

Closes gitlab-ce#56053

See merge request gitlab-org/gitlab-ee!10406

Update border radius of form controls and remove space above page titles

See merge request gitlab-org/gitlab-ce!24497

Fix static-analysis failures

Closes #10833

See merge request gitlab-org/gitlab-ee!10523

Add jQuery matchers to Jest

Closes #59637

See merge request gitlab-org/gitlab-ce!26722

This allows us to set the encoding of an IO passed without reading it
into memory.

This is useful if we want to stream files into Gitaly. Like we do when
uploading a new file to the repository.

Force a full GC after importing a project

Closes #59477

See merge request gitlab-org/gitlab-ce!26803

Add # frozen_string_literal to spec/workers

See merge request gitlab-org/gitlab-ce!26790

Remove find all tags feature flag

See merge request gitlab-org/gitlab-ce!26746

Refactor the pipeline feature spec

Closes #59747

See merge request gitlab-org/gitlab-ce!26822

Resolve "Should we translate severity values"

See merge request gitlab-org/gitlab-ee!10230

Fix Container Scanning for Kubernetes Runners

Closes gitlab-ee#5763 and gitlab-ee#6636

See merge request gitlab-org/gitlab-ce!26793

Add details for the first proof reader request

See merge request gitlab-org/gitlab-ce!26812