Due to a bug in our sidekiq middleware, post-update actions were not
being applied after changing assignees. This is fixed by changing
the format of the arguments to the background worker.

An unused worker is deleted, and we opt-in to the use of specialized
workers in the API, meaning we can delete some duplicated code.

Details of the fix:

This is vital to getting correct deduplication behavior in our sidekiq
middleware. The current logic is:

- CLIENT creates hash from worker queue name and arguments (calling
  `#to_s`)
- a job matching that hash is already running (in the working queue), it
  is not enqueued by the client.
- otherwise, the job is serialized and sent to the server
- SERVER pops the job and deserializes it
- the server runs the job
- The server calculates the deduplication hash, and deletes it, allowing
  similar jobs to be enqueued again.

This protocol relies on serialization being completely isomorphic. i.e.
`load . serialize === id`. If not, then the two hashes will not
match, and the deduplication block will remain up, and not be taken down
by the server.

The workaround in our case is to use a round-trippable hashmap (i.e.
string keys rather than symbols), since:

```
JSON.load({ 'x' => true}.to_json) == { 'x' => true }
```

but

```
JSON.load({ x: => true}.to_json) /= { x: => true }
```

See: https://gitlab.com/gitlab-com/gl-infra/scalability/-/issues/1090

Changelog: fixed

docs: Update Redis with the minimum version 5.0

See merge request gitlab-org/gitlab!62159

Hide billing plans with hide card attribute

See merge request gitlab-org/gitlab!61990

Remove Unicorn support: delete Unicorn Sampler

See merge request gitlab-org/gitlab!62090

Move gosec to alphabetical order

See merge request gitlab-org/gitlab!61948

Fix blob preview error

See merge request gitlab-org/gitlab!62128

Refactor LabelToken to use BaseToken

See merge request gitlab-org/gitlab!61992

Add description to 2 analytics metrics

See merge request gitlab-org/gitlab!62046

Set current project/group in WebHookWorker context [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!62130

Merge branch '331461-follow-template-development-guidelines-on-container-scanning-template' into 'master'

Follow template development guidelines for Container Scanning

See merge request gitlab-org/gitlab!62157

With removing Unicorn support in 14.0, UnicornSampler is no longer
needed.
Raindrops was only used with Unicorn, so it could be removed too.
Update the docs related to the change.

Changelog: removed

List requirements to see FE snowplow events

See merge request gitlab-org/gitlab!62077

Keyset paginator for AR::Relation

See merge request gitlab-org/gitlab!60412

Initial implementation of the ActiveRecord::Relation
keyset paginator.

Redirect some deprecated repository routes

See merge request gitlab-org/gitlab!34867

Disable ci_drop_cyclical_triggered_pipelines feature flag

See merge request gitlab-org/gitlab!62181

Return 404 from branches API when repository does not exist

See merge request gitlab-org/gitlab!62089

Fix design management references in the the data dictionary

See merge request gitlab-org/gitlab!62052

Fix argument help for Workhorse apiCiLongPollingDuration command

See merge request gitlab-org/gitlab!62150

Fix group_saml_enforced_sso_new_account_spec:35 end-to-end test

See merge request gitlab-org/gitlab!61975

Remove Unicorn support: update individual specs

See merge request gitlab-org/gitlab!62107

Add descriptions for BlobActionEnum

See merge request gitlab-org/gitlab!61817

Use the existence of ee/ directory in job rules

See merge request gitlab-org/gitlab!61758

Ignore labels remove_on_close column

See merge request gitlab-org/gitlab!62119

Move issue tracker integrations to the `Integrations::` namespace

See merge request gitlab-org/gitlab!61744

Merge branch '327736-add-extra-arguments-to-metric-yaml-defintion-for-filtering-data-in-instrumentation-class' into 'master'

Add options arguments to Redis HLL Metric YAML definition for filtering data in instrumentation class

See merge request gitlab-org/gitlab!61685

Add options arguments to Redis HLL Metric YAML definition for filtering data in instrumentation class

Check for credit card when playing manual jobs

See merge request gitlab-org/gitlab!62124

Prevent a user from running previously created manual jobs.

Changelog: fixed

Extract gitaly RPC backup strategy

See merge request gitlab-org/gitlab!61544