### 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.
run_type=run_type,
            dag_hash=dag_hash,
            creating_job_id=creating_job_id,
            data_interval=data_interval,
        )
        session.add(run)
        session.flush()
        run.dag = self
        
        
        run.verify_integrity(session=session)
        return run
    @classmethod
    @provide_session
    def bulk_sync_to_db(
        cls,
        dags: Collection[DAG],
        session=NEW_SESSION,
    ):
        """Use `airflow.models.DAG.bulk_write_to_db`, this method is deprecated."""
        warnings.warn(
            "This method is deprecated and will be removed in a future version. Please use bulk_write_to_db",
            RemovedInAirflow3Warning,
            stacklevel=2,
        )
        return cls.bulk_write_to_db(dags=dags, session=session)
    @classmethod
    @provide_session
    def bulk_write_to_db(
        cls,