Fix vacuum scheduler missing lock, locks never expiring (#19458)

Remove vacuuming of orphaned preview cards

spec/lib/vacuum/preview_cards_vacuum_spec.rb

@@ -28,9 +28,5 @@ RSpec.describe Vacuum::PreviewCardsVacuum do
     it 'does not delete attached preview cards' do
       expect(new_preview_card.reload).to be_persisted
     end
-
-    it 'deletes preview cards not attached to any status' do
-      expect { orphaned_preview_card.reload }.to raise_error ActiveRecord::RecordNotFound
-    end
   end
 end