**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
session = settings.Session()
        test_start_date = days_ago(2)
        dag = DAG(
            dag_id='test_sla_miss',
            default_args={'start_date': test_start_date, 'sla': datetime.timedelta(days=1)},
        )
        email1 = 'test1@test.com'
        task = DummyOperator(
            task_id='sla_missed', dag=dag, owner='airflow', email=email1, sla=datetime.timedelta(hours=1)
        )
        session.merge(TaskInstance(task=task, execution_date=test_start_date, state='Success'))
        email2 = 'test2@test.com'
        DummyOperator(task_id='sla_not_missed', dag=dag, owner='airflow', email=email2)
        session.merge(SlaMiss(task_id='sla_missed', dag_id='test_sla_miss', execution_date=test_start_date))
        dag_file_processor = DagFileProcessor(dag_ids=[], log=mock.MagicMock())
        dag_file_processor.manage_slas(dag=dag, session=session)
        assert len(mock_send_email.call_args_list) == 1
        send_email_to = mock_send_email.call_args_list[0][0][0]
        assert email1 in send_email_to
        assert email2 not in send_email_to
    @mock.patch('airflow.jobs.scheduler_job.Stats.incr')
    @mock.patch("airflow.utils.email.send_email")
    def test_dag_file_processor_sla_miss_email_exception(self, mock_send_email, mock_stats_incr):