**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
"""
        DagRuns with one failed and one successful root task -> SUCCESS
        """
        self.evaluate_dagrun(
            dag_id='test_dagrun_states_success',
            expected_task_states={
                'test_dagrun_fail': State.FAILED,
                'test_dagrun_succeed': State.SUCCESS,
            },
            dagrun_state=State.SUCCESS,
        )
    def test_dagrun_root_fail(self):
        """
        DagRuns with one successful and one failed root task -> FAILED
        """
        self.evaluate_dagrun(
            dag_id='test_dagrun_states_root_fail',
            expected_task_states={
                'test_dagrun_succeed': State.SUCCESS,
                'test_dagrun_fail': State.FAILED,
            },
            dagrun_state=State.FAILED,
        )
    def test_dagrun_root_fail_unfinished(self):