**Apache Airflow version**: 2.0.1
**Kubernetes version**: v1.19.7
**Executor**: KubernetesExecutor

**What happened**:

If you have a worker that gets stuck in pending forever, say with a missing volume mount, the task will stay in the queued state forever. Nothing is applying a timeout on it actually being able to start.

**What you expected to happen**:

Eventually the scheduler will notice that the worker hasn't progressed past pending after a given amount of time and will mark it as a failure.

**How to reproduce it**:
```python
from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.utils.dates import days_ago
from kubernetes.client import models as k8s


default_args = {
    "owner": "airflow",
}

with DAG(
    dag_id="pending",
    default_args=default_args,
    schedule_interval=None,
    start_date=days_ago(2),
) as dag:
    BashOperator(
        task_id="forever_pending",
        bash_command="date; sleep 30; date",
        executor_config={
            "pod_override": k8s.V1Pod(
                spec=k8s.V1PodSpec(
                    containers=[
                        k8s.V1Container(
                            name="base",
                            volume_mounts=[
                                k8s.V1VolumeMount(mount_path="/foo/", name="vol")
                            ],
                        )
                    ],
                    volumes=[
                        k8s.V1Volume(
                            name="vol",
                            persistent_volume_claim=k8s.V1PersistentVolumeClaimVolumeSource(
                                claim_name="missing"
                            ),
                        )
                    ],
                )
            ),
        },
    )
```


**Anything else we need to know**:
Related to:

* #15149 (This is reporting that these pending pods don't get deleted via "Mark Failed")
* #14556 (This handles when these pending pods get deleted and is already fixed)

airflow/jobs/scheduler_job.py
"""
        If there are tasks left over in the executor,
        we set them back to SCHEDULED to avoid creating hanging tasks.
        :param session: session for ORM operations
        """
        if not self.executor.queued_tasks:
            return
        filter_for_ti_state_change = [
            and_(
                TI.dag_id == dag_id,
                TI.task_id == task_id,
                TI.execution_date == execution_date,
                
                
                TI._try_number == try_number - 1,  
                TI.state == State.QUEUED,
            )
            for dag_id, task_id, execution_date, try_number in self.executor.queued_tasks.keys()
        ]
        ti_query = session.query(TI).filter(or_(*filter_for_ti_state_change))
        tis_to_set_to_scheduled: List[TI] = with_row_locks(ti_query, session=session).all()
        if not tis_to_set_to_scheduled:
            return
        
        filter_for_tis = TI.filter_for_tis(tis_to_set_to_scheduled)
        session.query(TI).filter(filter_for_tis).update(
            {TI.state: State.SCHEDULED, TI.queued_dttm: None}, synchronize_session=False