**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/dag.py
self._concurrency = value
    @property
    def access_control(self):
        return self._access_control
    @access_control.setter
    def access_control(self, value):
        self._access_control = DAG._upgrade_outdated_dag_access_control(value)
    @property
    def description(self) -> Optional[str]:
        return self._description
    @property
    def default_view(self) -> str:
        return self._default_view
    @property
    def pickle_id(self) -> Optional[int]:
        return self._pickle_id
    @pickle_id.setter
    def pickle_id(self, value: int) -> None:
        self._pickle_id = value
    def param(self, name: str, default=None) -> DagParam:
        """
        Return a DagParam object for current dag.
        :param name: dag parameter name.
        :param default: fallback value for dag parameter.
        :return: DagParam instance for specified name and current dag.
        """
        return DagParam(current_dag=self, name=name, default=default)
    @property
    def tasks(self) -> List[BaseOperator]: