This tests fails occasionally on mysql at least:

https://github.com/apache/airflow/pull/11555/checks?check_run_id=1260840314#step:9:1125

```
=================================== FAILURES ===================================
_____________ TestSchedulerJob.test_no_orphan_process_will_be_left _____________

self = <tests.jobs.test_scheduler_job.TestSchedulerJob testMethod=test_no_orphan_process_will_be_left>

    def test_no_orphan_process_will_be_left(self):
        empty_dir = mkdtemp()
        current_process = psutil.Process()
        old_children = current_process.children(recursive=True)
        scheduler = SchedulerJob(subdir=empty_dir,
                                 num_runs=1,
                                 executor=MockExecutor(do_update=False))
        scheduler.run()
        shutil.rmtree(empty_dir)
    
        # Remove potential noise created by previous tests.
        current_children = set(current_process.children(recursive=True)) - set(
            old_children)
>       self.assertFalse(current_children)
E       AssertionError: {psutil.Process(pid=3474, name='/usr/local/bin/', status='running', started='19:26:22')} is not false

tests/jobs/test_scheduler_job.py:871: AssertionError
```



tests/jobs/test_scheduler_job.py
dag = DAG(dag_id='dag_id', start_date=DEFAULT_DATE)
        task = DummyOperator(task_id='task_id', dag=dag, owner='airflow')
        dag = SerializedDAG.from_dict(SerializedDAG.to_dict(dag))
        
        session = settings.Session()
        scheduler_job = SchedulerJob(subdir=os.devnull)
        mock_logger = mock.MagicMock()
        test_executor = MockExecutor(do_update=False)
        scheduler_job.executor = test_executor
        scheduler_job._logger = mock_logger
        scheduler_job._change_state_for_tasks_failed_to_execute()  
        mock_logger.info.assert_not_called()
        
        session.query(TaskInstance).delete()
        session.commit()
        key = 'dag_id', 'task_id', DEFAULT_DATE, 1
        test_executor.queued_tasks[key] = 'value'
        ti = TaskInstance(task, DEFAULT_DATE)
        ti.state = State.QUEUED
        session.merge(ti)