Improve IP cleanup query (mastodon#11871)

Author: abcang

app/workers/scheduler/ip_cleanup_scheduler.rb

@@ -9,7 +9,7 @@ class Scheduler::IpCleanupScheduler
 
   def perform
     time_ago = RETENTION_PERIOD.ago
-    SessionActivation.where('updated_at < ?', time_ago).destroy_all
-    User.where('last_sign_in_at < ?', time_ago).update_all(last_sign_in_ip: nil)
+    SessionActivation.where('updated_at < ?', time_ago).in_batches.destroy_all
+    User.where('last_sign_in_at < ?', time_ago).where.not(last_sign_in_ip: nil).in_batches.update_all(last_sign_in_ip: nil)
   end
 end