Fix performance on instances list in admin UI (#15282)

- Reduce duplicate queries
- Remove n+1 queries
- Add accounts count to detailed view
- Add separate action log entry for updating existing domain blocks

app/workers/scheduler/instance_refresh_scheduler.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class Scheduler::InstanceRefreshScheduler
+  include Sidekiq::Worker
+
+  sidekiq_options lock: :until_executed, retry: 0
+
+  def perform
+    Instance.refresh
+  end
+end