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

config/sidekiq.yml

@@ -36,3 +36,6 @@
   pghero_scheduler:
     cron: '0 0 * * *'
     class: Scheduler::PgheroScheduler
+  instance_refresh_scheduler:
+    cron: '0 * * * *'
+    class: Scheduler::InstanceRefreshScheduler