Change search indexing to use batches to minimize resource usage (#18451)

config/sidekiq.yml

@@ -21,6 +21,10 @@
     every: '6h'
     class: Scheduler::Trends::ReviewNotificationsScheduler
     queue: scheduler
+  indexing_scheduler:
+    every: '5m'
+    class: Scheduler::IndexingScheduler
+    queue: scheduler
   media_cleanup_scheduler:
     cron: '<%= Random.rand(0..59) %> <%= Random.rand(3..5) %> * * *'
     class: Scheduler::MediaCleanupScheduler