Fix Sidekiq warnings about JSON serialization (#17381)

* Fix Sidekiq warnings about JSON serialization

This occurs on every symbol argument we pass, and every symbol key in hashes,
because Sidekiq expects strings instead.

See https://github.com/mperham/sidekiq/pull/5071

We do not need to change how workers parse their arguments because this has
not changed and we were already converting to symbols adequately or using
`with_indifferent_access`.

* Set Sidekiq to raise on unsafe arguments in test mode

In order to more easily catch issues that would produce warnings in production
code.

app/services/activitypub/process_status_update_service.rb

@@ -266,7 +266,7 @@ class ActivityPub::ProcessStatusUpdateService < BaseService
   end
 
   def broadcast_updates!
-    ::DistributionWorker.perform_async(@status.id, update: true)
+    ::DistributionWorker.perform_async(@status.id, { 'update' => true })
   end
 
   def queue_poll_notifications!