**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 if a task instance will be added if the dag is updated
        """
        dag = DAG(dag_id='test_scheduler_add_new_task', start_date=DEFAULT_DATE)
        BashOperator(task_id='dummy', dag=dag, owner='airflow', bash_command='echo test')
        scheduler = SchedulerJob(subdir=os.devnull)
        scheduler.dagbag.bag_dag(dag, root_dag=dag)
        
        with mock.patch.object(settings, "STORE_DAG_CODE", False):
            scheduler.dagbag.sync_to_db()
        session = settings.Session()
        orm_dag = session.query(DagModel).get(dag.dag_id)
        assert orm_dag is not None
        scheduler = SchedulerJob(subdir=os.devnull)
        scheduler.processor_agent = mock.MagicMock()
        dag = scheduler.dagbag.get_dag('test_scheduler_add_new_task', session=session)
        scheduler._create_dag_runs([orm_dag], session)
        drs = DagRun.find(dag_id=dag.dag_id, session=session)
        assert len(drs) == 1
        dr = drs[0]
        tis = dr.get_task_instances()
        assert len(tis) == 1
        BashOperator(task_id='dummy2', dag=dag, owner='airflow', bash_command='echo test')
        SerializedDagModel.write_dag(dag=dag)
        scheduled_tis = scheduler._schedule_dag_run(dr, set(), session)
        session.flush()