**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
.options(joinedload(DagModel.tags, innerjoin=False))
            .filter(DagModel.dag_id.in_(dag_ids))
        )
        orm_dags = with_row_locks(query, of=DagModel, session=session).all()
        existing_dag_ids = {orm_dag.dag_id for orm_dag in orm_dags}
        missing_dag_ids = dag_ids.difference(existing_dag_ids)
        for missing_dag_id in missing_dag_ids:
            orm_dag = DagModel(dag_id=missing_dag_id)
            dag = dag_by_ids[missing_dag_id]
            if dag.is_paused_upon_creation is not None:
                orm_dag.is_paused = dag.is_paused_upon_creation
            orm_dag.tags = []
            log.info("Creating ORM DAG for %s", dag.dag_id)
            session.add(orm_dag)
            orm_dags.append(orm_dag)
        
        most_recent_dag_runs = dict(
            session.query(DagRun.dag_id, func.max_(DagRun.execution_date))
            .filter(
                DagRun.dag_id.in_(existing_dag_ids),
                or_(
                    DagRun.run_type == DagRunType.BACKFILL_JOB,
                    DagRun.run_type == DagRunType.SCHEDULED,
                ),
            )
            .group_by(DagRun.dag_id)
            .all()
        )
        
        num_active_runs = dict(