### 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.
"""
        Pause/Un-pause a DAG.
        :param is_paused: Is the DAG paused
        :param including_subdags: whether to include the DAG's subdags
        :param session: session
        """
        filter_query = [
            DagModel.dag_id == self.dag_id,
        ]
        if including_subdags:
            filter_query.append(DagModel.root_dag_id == self.dag_id)
        session.execute(
            update(DagModel)
            .where(or_(*filter_query))
            .values(is_paused=is_paused)
            .execution_options(synchronize_session="fetch")
        )
        session.commit()
    @classmethod
    @internal_api_call
    @provide_session
    def deactivate_deleted_dags(