### 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.
if end_date or not self.allow_future_exec_dates:
            end_date = end_date or timezone.utcnow()
            tis = tis.where(DagRun.execution_date <= end_date)
        if state:
            if isinstance(state, (str, TaskInstanceState)):
                tis = tis.where(TaskInstance.state == state)
            elif len(state) == 1:
                tis = tis.where(TaskInstance.state == state[0])
            else:
                
                if None in state:
                    if all(x is None for x in state):
                        tis = tis.where(TaskInstance.state.is_(None))
                    else:
                        not_none_state = [s for s in state if s]
                        tis = tis.where(
                            or_(TaskInstance.state.in_(not_none_state), TaskInstance.state.is_(None))
                        )
                else:
                    tis = tis.where(TaskInstance.state.in_(state))
        
        if include_parentdag and self.parent_dag is not None:
            if visited_external_tis is None:
                visited_external_tis = set()
            p_dag = self.parent_dag.partial_subset(
                task_ids_or_regex=r"^{}$".format(self.dag_id.split(".")[1]),
                include_upstream=False,
                include_downstream=True,
            )