Change preview card deletes to be done using batch method (#28183)

app/lib/vacuum/preview_cards_vacuum.rb

@@ -14,9 +14,8 @@ class Vacuum::PreviewCardsVacuum
   private
 
   def vacuum_cached_images!
-    preview_cards_past_retention_period.find_each do |preview_card|
-      preview_card.image.destroy
-      preview_card.save
+    preview_cards_past_retention_period.find_in_batches do |preview_card|
+      AttachmentBatch.new(PreviewCard, preview_card).clear
     end
   end