### Body

Currently `start_date` is mandatory parameter.
For DAGs with `schedule=None` we can relax this requirement as no scheduling calculation needed so the `start_date` parameter isn't used.

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
def generate_run_id(self, *, run_type, logical_date, data_interval, **extra) -> str:
            return "abc"
    dag = DAG(dag_id="test", start_date=DEFAULT_DATE, schedule=CustomRunIdTimetable())
    dag_run = dag.create_dagrun(
        run_type=DagRunType.MANUAL,
        state=DagRunState.QUEUED,
        execution_date=DEFAULT_DATE,
        data_interval=(DEFAULT_DATE, DEFAULT_DATE),
    )
    assert dag_run.run_id == "abc"
@pytest.mark.parametrize(
    "run_id_type",
    [DagRunType.BACKFILL_JOB, DagRunType.SCHEDULED, DagRunType.DATASET_TRIGGERED],
)
def test_create_dagrun_disallow_manual_to_use_automated_run_id(run_id_type: DagRunType) -> None:
    dag = DAG(dag_id="test", start_date=DEFAULT_DATE, schedule="@daily")
    run_id = run_id_type.generate_run_id(DEFAULT_DATE)
    with pytest.raises(ValueError) as ctx:
        dag.create_dagrun(
            run_type=DagRunType.MANUAL,
            run_id=run_id,
            execution_date=DEFAULT_DATE,
            data_interval=(DEFAULT_DATE, DEFAULT_DATE),
            state=DagRunState.QUEUED,
        )
    assert str(ctx.value) == (
        f"A manual DAG run cannot use ID {run_id!r} since it is reserved for {run_id_type.value} runs"
    )
class TestTaskClearingSetupTeardownBehavior: