**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
([20, 11, 11, 11], 1, 1, "1d", "@once", "linear"),  
            ([20, 21, 23, 25], 1, 1, "1d", "30m", "no_structure"),  
            ([20, 21, 23, 25], 1, 1, "1d", "30m", "linear"),  
            ([20, 21, 23, 25], 1, 1, "1d", "30m", "binary_tree"),  
            ([20, 21, 23, 25], 1, 1, "1d", "30m", "star"),  
            ([20, 21, 23, 25], 1, 1, "1d", "30m", "grid"),  
            
            ([8, 8, 8, 8], 1, 5, "1d", "None", "no_structure"),  
            ([8, 8, 8, 8], 1, 5, "1d", "None", "linear"),  
            ([20, 11, 11, 11], 1, 5, "1d", "@once", "no_structure"),  
            ([21, 12, 12, 12], 1, 5, "1d", "@once", "linear"),  
            ([20, 21, 23, 25], 1, 5, "1d", "30m", "no_structure"),  
            ([21, 23, 26, 29], 1, 5, "1d", "30m", "linear"),  
            ([21, 23, 26, 29], 1, 5, "1d", "30m", "binary_tree"),  
            ([21, 23, 26, 29], 1, 5, "1d", "30m", "star"),  
            ([21, 23, 26, 29], 1, 5, "1d", "30m", "grid"),  
            
            ([8, 8, 8, 8], 10, 10, "1d", "None", "no_structure"),  
            ([8, 8, 8, 8], 10, 10, "1d", "None", "linear"),  
            ([83, 26, 26, 26], 10, 10, "1d", "@once", "no_structure"),  
            ([93, 39, 39, 39], 10, 10, "1d", "@once", "linear"),  
            ([83, 87, 87, 87], 10, 10, "1d", "30m", "no_structure"),  
            ([93, 113, 113, 113], 10, 10, "1d", "30m", "linear"),  
            ([93, 107, 107, 107], 10, 10, "1d", "30m", "binary_tree"),  
            ([93, 107, 107, 107], 10, 10, "1d", "30m", "star"),  
            ([93, 107, 107, 107], 10, 10, "1d", "30m", "grid"),  
        ]
    )
    @pytest.mark.quarantined
    def test_process_dags_queries_count(