Remove unused IssuesChannel

With 
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/59958 
in production, we no longer need this code.

There's no impact to the user since the same feature is
now implemented using GraphQL subscriptions.

See merge request gitlab-org/gitlab!61800

Merge branch '273322-fy21q4-foundations-kr2-audit-and-update-buttons-on-projects-tagscontroller-index' into 'master'

Audit and update buttons on Projects::TagsController#index"

See merge request gitlab-org/gitlab!61413

Flush statistics cache anytime it is updated

See merge request gitlab-org/gitlab!52938

`Projects::UpdateStatisticsService` attempts to refresh project
statistics, but it relies the caller to flush the existing statistics
cache for the repository. If the flush doesn't happen, the refresh won't
actually do anything. For example, this might be happening in
`ProjectCacheWorker`.

We now expire the stats inside the service to ensure consistent results.

This came out of
https://gitlab.com/gitlab-org/gitlab/-/issues/255001.

https://gitlab.com/gitlab-org/gitlab/-/merge_requests/52938

Update old temporary NuGet packages to processing

See merge request gitlab-org/gitlab!61724

Add body to finding evidence responses

See merge request gitlab-org/gitlab!61631

Change 'Administrators' to 'Owners' under minimal access section

See merge request gitlab-org/gitlab!61760

Add a boolean column for tracking MR draft status

See merge request gitlab-org/gitlab!61681

Edit to alert drawer doc

See merge request gitlab-org/gitlab!61809

Address technical debt in job_container_item component

See merge request gitlab-org/gitlab!61726

Add style guide for YAML reference

See merge request gitlab-org/gitlab!61780

Reduces page_bundle CSS for TODO list

See merge request gitlab-org/gitlab!60784

Improve user experience in terms of performance

Changelog: fixed
Co-authored-by: Phil Hughes <me@iamphill.com>
Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

Add three stage pipeline template

See merge request gitlab-org/gitlab!61762

Prevent future timestamps in migration filenames

See merge request gitlab-org/gitlab!61473

Remove Rails from CI templates and fix LaTeX spelling

See merge request gitlab-org/gitlab!61599

Add a new error modal for billable members

See merge request gitlab-org/gitlab!61509

Some billable members can be associated via group invites, which makes
them invalid for removal from the group being viewed. This will now
trigger an error modal to inform the customer

Changelog: changed

Add nuget metadata type to Package GraphQl type

See merge request gitlab-org/gitlab!61695

Combine feature tests for checking issue card info

See merge request gitlab-org/gitlab!61707

Modify sentry for big pipeline graph

See merge request gitlab-org/gitlab!61818

Add feature spec for product marketing emails setting

See merge request gitlab-org/gitlab!61578

Correctly fetch labels in GraphQL boards sidebar [RUN-AS-IF-FOSS]

See merge request gitlab-org/gitlab!61423

Docs: clarify connection between SCM and code review in shared features

See merge request gitlab-org/gitlab!61010

Add note to registry docs about manifest lists and GC

See merge request gitlab-org/gitlab!61788

Update scanner maintenance section with information about Trivy

See merge request gitlab-org/gitlab!61748

Add documentation about `projects/remote-import` endpoint

See merge request gitlab-org/gitlab!61715

Add CTA buttons & track their usage

See merge request gitlab-org/gitlab!58832