Clear clearable jobs in a loop instead of batching

ActiveRecord batching can be slow when looping over records filtered by
non-PKs. We don't care about the order of deletion here, so we can just use a loop
to delete the clearable jobs; this allows to achieve better performance
in general.

Author: intrip

app/models/solid_queue/job/clearable.rb

@@ -11,7 +11,10 @@ module Clearable
 
       class_methods do
         def clear_finished_in_batches(batch_size: 500, finished_before: SolidQueue.clear_finished_jobs_after.ago)
-          clearable(finished_before: finished_before).in_batches(of: batch_size).delete_all
+          loop do
+            records_deleted = clearable(finished_before: finished_before).limit(batch_size).delete_all
+            break if records_deleted == 0
+          end
         end
       end
     end