When we switched from a single-threaded application server (Unicorn) to
a multithreaded one (Puma), we did not realize that Puma often reaps
threads after a request is done and recreates them later. This makes the
thread-local cache ineffective, as the cache does not store anything
beyond the lifetime of the thread.

Since `ActiveSupport::Cache::MemoryStore` is thread-safe, we should be
able to switch the L1 cache for feature flags to use this to reduce load
on Redis.

Since read and write access is synchronized, this does have the side
effect of adding contention when feature flags are accessed.

Discovered in
https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/9414

Add link to community forum for migration guide

See merge request gitlab-org/gitlab!26882

Change introduction wording

See merge request gitlab-org/gitlab!26916

Add "GitLab for Jenkins Users" context to migration doc

See merge request gitlab-org/gitlab!26893

API endpoint to list deploy tokens in a group

See merge request gitlab-org/gitlab!25219

Upgrade ActiveSupport in QA

See merge request gitlab-org/gitlab!26752

Fix docs-lint job that was missing half the docs

See merge request gitlab-org/gitlab!26951

Partly support `monaco-editor` in Jest

See merge request gitlab-org/gitlab!26396

Bump Auto Deploy image to v0.12.1

See merge request gitlab-org/gitlab!26336

Added mention of EDU and OSS programs

See merge request gitlab-org/gitlab!26637

Update snippets test to ignore visibility case

Closes #209928

See merge request gitlab-org/gitlab!26933

It just needed an update so there's no need to monitor it
in quarantine.

Change capybara screenshots files names

See merge request gitlab-org/gitlab!26788

This MR updates our screenshots files names taken on test failures:
- Remove timestamps
- Use RSpec full_description method instead of the file_path

Two new backwards compatible features:

- Allow replicas to be set to zero
- Add option to install and use postgres chart 8.2.1

Add docs on how to use the postgres chart 8.2.1 to be able to deploy to
a Kubernetes 1.16+ cluster.

This matches the version we use in Rails

Enable license compliance for local intalls

See merge request gitlab-org/gitlab!26770

* Default feature flag to true

Add changelog

Geo docs: Update data type limitations

See merge request gitlab-org/gitlab!26816

Optimize mirrored project counters with pipelines enabled

See merge request gitlab-org/gitlab!26802

- needed for failing counters on .com due
  to long queries

Clarify that subgroups can have a maximum ancestry of 21

See merge request gitlab-org/gitlab!26829

Add WAF anomaly aggregation queries

See merge request gitlab-org/gitlab!24837

GraphQL: Migrate from the TimeoutMiddleware to the Timeout plugin

See merge request gitlab-org/gitlab!26822

Add documentation for Jira dev panel with App

See merge request gitlab-org/gitlab!26104

There is a new way to use the Jira dev panel.
On GitLab.com and Jira cloud, the GitLab App
can be used instead of the DVCS connector.

This commit adds the missing documentation
about setting up the GitLab for Jira App.

Fix smartcard param check in User::BuildService

Closes #33641

See merge request gitlab-org/gitlab!26800

Quarantine test because of #209928

See merge request gitlab-org/gitlab!26930

Introduce database table to store users statistics

See merge request gitlab-org/gitlab!26261

Merge branch '12420-prevent-projects-from-being-shared-outside-a-gma-group-member-fork' into 'master'

Resolve "Prevent projects from being shared outside a GMA group" - adding member to forked project

Closes #12420

See merge request gitlab-org/gitlab!26186

Do not add approvers as participants of each merge request

Closes #616

See merge request gitlab-org/gitlab!25546

This also removes automatic email notifications for approvers and
quite a few specs referencing them.

Make Commit#has_been_reverted? cheaper

Closes #21049 and #199197

See merge request gitlab-org/gitlab!26784

Preload DB records in bulk ES indexing

See merge request gitlab-org/gitlab!26754