**Apache Airflow version**:

1.10.12

**What happened**:

I created dag with dagrun_timeout=2 minutes. 

After 2 minutes dagrun is marked as failed and the next one is started, but task keeps going.

**What you expected to happen**:

Task is killed with dag run as it is done when you mark dagrun failed manually.

**How to reproduce it**:
```
dag = DAG(dag_id='platform.airflow-test',
          description='',
          schedule_interval="0 0 * * *",
          start_date=datetime(2020, 7, 1),
          max_active_runs=1,
          catchup=True,
          dagrun_timeout=timedelta(minutes=2))

run_this = BashOperator(
    task_id='run_after_loop',
    bash_command=' for((i=1;i<=600;i+=1)); do echo "Welcome $i times"; sleep 1;  done',
    dag=dag,
)
```
tests/jobs/test_scheduler_job.py
self,
        dag_id,
        expected_task_states,  
        dagrun_state,
        run_kwargs=None,
        advance_execution_date=False,
        session=None,
    ):  
        """
        Helper for testing DagRun states with simple two-task DAGS.
        This is hackish: a dag run is created but its tasks are
        run by a backfill.
        """
        if run_kwargs is None:
            run_kwargs = {}
        dag = self.dagbag.get_dag(dag_id)
        dr = dag.create_dagrun(
            run_type=DagRunType.SCHEDULED,
            execution_date=dag.next_dagrun_after_date(None),
            state=State.RUNNING,
        )
        if advance_execution_date: