### 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
self, dag_maker_fixture, dag_id='test_dag', max_active_runs=1, **kwargs
    ):
        with dag_maker_fixture(
            dag_id=dag_id,
            schedule_interval="@hourly",
            max_active_runs=max_active_runs,
            **kwargs,
        ) as dag:
            op1 = DummyOperator(task_id='leave1')
            op2 = DummyOperator(task_id='leave2')
            op3 = DummyOperator(task_id='upstream_level_1')
            op4 = DummyOperator(task_id='upstream_level_2')
            op1 >> op2 >> op3
            op4 >> op3
        return dag
    def test_backfill_max_limit_check_within_limit(self, dag_maker):