### Body

Add unit test for changes in https://github.com/apache/airflow/pull/17305

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
tests/jobs/test_backfill_job.py
start_date = DEFAULT_DATE
        end_date = DEFAULT_DATE
        
        dag = self._get_dag_test_max_active_limits(
            dag_maker, dag_id='test_backfill_max_limit_check_no_count_existing'
        )
        dag_maker.create_dagrun()
        executor = MockExecutor()
        job = BackfillJob(
            dag=dag, start_date=start_date, end_date=end_date, executor=executor, donot_pickle=True
        )
        job.run()
        
        
        dagruns = DagRun.find(dag_id=dag.dag_id)
        
        
        assert 1 == len(dagruns)
        assert State.SUCCESS == dagruns[0].state
    def test_backfill_max_limit_check_complete_loop(self, dag_maker):