**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
"""
        Test that the dag file processor does not call the sla_miss_callback when a
        notification has already been sent
        """
        session = settings.Session()
        
        sla_callback = MagicMock()
        
        
        test_start_date = days_ago(2)
        dag = DAG(
            dag_id='test_sla_miss',
            sla_miss_callback=sla_callback,
            default_args={'start_date': test_start_date, 'sla': datetime.timedelta(days=1)},
        )
        task = DummyOperator(task_id='dummy', dag=dag, owner='airflow')
        
        session.merge(TaskInstance(task=task, execution_date=test_start_date, state='success'))
        
        session.merge(
            SlaMiss(
                task_id='dummy',
                dag_id='test_sla_miss',
                execution_date=test_start_date,
                email_sent=False,
                notification_sent=True,
            )
        )