**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
return TaskInstance(task=self.task, execution_date=previous_scheduled_date)
            dr.dag = dag
            
            
            
            ignore_schedule = state is not None or dag.schedule_interval is None
            if dag.catchup is True and not ignore_schedule:
                last_dagrun = dr.get_previous_scheduled_dagrun(session=session)
            else:
                last_dagrun = dr.get_previous_dagrun(session=session, state=state)
            if last_dagrun:
                return last_dagrun.get_task_instance(self.task_id, session=session)
        return None
    @property
    def previous_ti(self):
        """
        This attribute is deprecated.
        Please use `airflow.models.taskinstance.TaskInstance.get_previous_ti` method.
        """
        warnings.warn(
            """
            This attribute is deprecated.
            Please use `airflow.models.taskinstance.TaskInstance.get_previous_ti` method.
            """,
            DeprecationWarning,
            stacklevel=2,
        )
        return self.get_previous_ti()
    @property
    def previous_ti_success(self) -> Optional['TaskInstance']: