**Apache Airflow version**: 2.0.0


**Kubernetes version (if you are using kubernetes)** (use `kubectl version`):

**Environment**:

- **Cloud provider or hardware configuration**:
- **OS** (e.g. from /etc/os-release):
- **Kernel** (e.g. `uname -a`):
- **Install tools**:
- **Others**:

**What happened**:

I have the following DAG:

```py
from datetime import datetime, timedelta

from airflow import DAG
from airflow.operators.bash_operator import BashOperator

with DAG(
    dag_id="sla_trigger",
    schedule_interval="* * * * *",
    start_date=datetime(2020, 2, 3),
) as dag:
    BashOperator(
        task_id="bash_task",
        bash_command="sleep 30",
        sla=timedelta(seconds=2),
    )

```

And in my understanding this dag should result in SLA miss every time it is triggered (every minute). However, after few minutes of running I don't see any SLA misses...

**What you expected to happen**:

I expect to see SLA if task takes longer than expected.

**How to reproduce it**:

Use the dag from above.

**Anything else we need to know**:

N/A

tests/jobs/test_scheduler_job.py
"""
        Test if a a dagrun will not be scheduled if max_dag_runs
        has been reached and dagrun_timeout is not reached
        Test if a a dagrun would be scheduled if max_dag_runs has
        been reached but dagrun_timeout is also reached
        """
        dag = DAG(dag_id='test_scheduler_verify_max_active_runs_and_dagrun_timeout', start_date=DEFAULT_DATE)
        dag.max_active_runs = 1
        dag.dagrun_timeout = datetime.timedelta(seconds=60)
        DummyOperator(task_id='dummy', dag=dag, owner='airflow')
        scheduler = SchedulerJob(subdir=os.devnull)
        scheduler.dagbag.bag_dag(dag, root_dag=dag)
        scheduler.dagbag.sync_to_db()
        session = settings.Session()
        orm_dag = session.query(DagModel).get(dag.dag_id)
        assert orm_dag is not None
        dag = SerializedDAG.from_dict(SerializedDAG.to_dict(dag))
        scheduler = SchedulerJob(subdir=os.devnull)
        scheduler._create_dag_runs([orm_dag], session)
        drs = DagRun.find(dag_id=dag.dag_id, session=session)
        assert len(drs) == 1