**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
installed. This command is part of the message sent to executors by
        the orchestrator.
        """
        dag = self.task.dag
        should_pass_filepath = not pickle_id and dag
        if should_pass_filepath and dag.full_filepath != dag.filepath:
            path = f"DAGS_FOLDER/{dag.filepath}"
        elif should_pass_filepath and dag.full_filepath:
            path = dag.full_filepath
        else:
            path = None
        return TaskInstance.generate_command(
            self.dag_id,
            self.task_id,
            self.execution_date,
            mark_success=mark_success,
            ignore_all_deps=ignore_all_deps,
            ignore_task_deps=ignore_task_deps,
            ignore_depends_on_past=ignore_depends_on_past,
            ignore_ti_state=ignore_ti_state,
            local=local,
            pickle_id=pickle_id,
            file_path=path,
            raw=raw,
            job_id=job_id,
            pool=pool,
            cfg_path=cfg_path,
        )
    @staticmethod
    def generate_command(