**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

airflow/jobs/scheduler_job.py
.filter(models.TaskInstance.dag_id.in_(list(self.dagbag.dag_ids)))
            .filter(models.TaskInstance.state.in_(old_states))
            .filter(
                or_(
                    
                    models.DagRun.state != State.RUNNING,
                    
                    models.DagRun.state.is_(None),
                )
            )
        )
        
        
        if self.using_sqlite or self.using_mysql:
            tis_to_change: List[TI] = with_row_locks(
                query, of=TI, session=session, **skip_locked(session=session)
            ).all()
            for ti in tis_to_change:
                ti.set_state(new_state, session=session)
                tis_changed += 1
        else:
            subq = query.subquery()
            current_time = timezone.utcnow()
            ti_prop_update = {
                models.TaskInstance.state: new_state,
                models.TaskInstance.start_date: current_time,
            }
            
            if new_state in State.finished:
                ti_prop_update.update(