**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.

tests/sensors/test_external_task_sensor.py
"""
    Create a DagBag containing two DAGs, linked by multiple ExternalTaskMarker.
    """
    dag_bag = DagBag(dag_folder=DEV_NULL, include_examples=False)
    daily_dag = DAG("daily_dag", start_date=DEFAULT_DATE, schedule_interval="@daily")
    agg_dag = DAG("agg_dag", start_date=DEFAULT_DATE, schedule_interval="@daily")
    dag_bag.bag_dag(dag=daily_dag, root_dag=daily_dag)
    dag_bag.bag_dag(dag=agg_dag, root_dag=agg_dag)
    daily_task = DummyOperator(task_id="daily_tas", dag=daily_dag)
    start = DummyOperator(task_id="start", dag=agg_dag)
    for i in range(25):
        task = ExternalTaskMarker(
            task_id=f"{daily_task.task_id}_{i}",
            external_dag_id=daily_dag.dag_id,
            external_task_id=daily_task.task_id,
            execution_date="{{ macros.ds_add(ds, -1 * %s) }}" % i,
            dag=agg_dag,
        )
        start >> task
    yield dag_bag
@pytest.mark.quarantined
@pytest.mark.backend("postgres", "mysql")
def test_clear_multiple_external_task_marker(dag_bag_multiple):