Remove ensure from with_transaction_returning_status

The test added in 12b0b26d passes even
without this code since 9b8c7796, as the
call to `id` in `remember_transaction_record_state` now triggers a
`sync_with_transaction_state` which discards the leftover state from the
previous transaction.

This issue had already been fixed for `save!`, `destroy` and `touch` in
caae79a3, but continued to affect `save`
because the call to `rollback_active_record_state!` in that method would
increment the transaction level before `add_to_transaction` could clear
it, preventing the fix from working correctly.

As `rollback_active_record_state!` was removed entirely in
48007d53, this code is no longer needed.

activerecord/lib/active_record/transactions.rb

@@ -375,10 +375,6 @@ def with_transaction_returning_status
         raise ActiveRecord::Rollback unless status
       end
       status
-    ensure
-      if @transaction_state && @transaction_state.committed?
-        clear_transaction_record_state
-      end
     end
 
     private