**Apache Airflow version**:

2.0.1

**What happened**:

When clearing task across dags using `ExternalTaskMarker` the dag state of the external `DagRun` is not set to active. So cleared tasks in the external dag will not automatically start if the `DagRun` is a Failed or Succeeded state.

**What you expected to happen**:

The external `DagRun` run should also be set to Running state.

**How to reproduce it**:

Clear tasks in an external dag using an ExternalTaskMarker.


**Anything else we need to know**:

Looking at the code is has:

https://github.com/apache/airflow/blob/b23fc137812f5eabf7834e07e032915e2a504c17/airflow/models/dag.py#L1323-L1335

It seems like it intentionally calls the dag member method `set_dag_run_state` instead of letting the helper function `clear_task_insntances` set the `DagRun` state. But the member method will only change the state of `DagRun`s of dag where the original task is, while I believe `clear_task_instances` would correctly change the state of all involved `DagRun`s.

airflow/models/taskinstance.py
self.dag_id,
            self.task_id,
            self._safe_date('execution_date', '%Y%m%dT%H%M%S'),
            self._safe_date('start_date', '%Y%m%dT%H%M%S'),
            self._safe_date('end_date', '%Y%m%dT%H%M%S'),
        )
        if email_for_state and task.email:
            try:
                self.email_alert(error)
            except Exception:  
                self.log.exception('Failed to send email to: %s', task.email)
        if not test_mode:
            session.merge(self)
        session.commit()
    @provide_session
    def handle_failure_with_callback(
        self,
        error: Union[str, Exception],
        test_mode: Optional[bool] = None,
        force_fail: bool = False,
        session=None,
    ) -> None:
        self.handle_failure(error=error, test_mode=test_mode, force_fail=force_fail, session=session)
        self._run_finished_callback(error=error)
    def is_eligible_to_retry(self):
        """Is task instance is eligible for retry"""
        return self.task.retries and self.try_number <= self.max_tries
    def _safe_date(self, date_attr, fmt):
        result = getattr(self, date_attr, None)
        if result is not None: