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
state=State.FAILED,
            execution_date=DEFAULT_DATE + timedelta(days=1),
            start_date=DEFAULT_DATE + timedelta(days=1),
            session=session,
        )
        ti = dr.get_task_instance(task_id=op1.task_id, session=session)
        ti.state = initial_task_state
        session.commit()
        
        
        scheduler = SchedulerJob(num_runs=2, processor_poll_interval=30)
        scheduler.dagbag = dagbag
        executor = MockExecutor(do_update=False)
        executor.queued_tasks
        scheduler.executor = executor
        processor = mock.MagicMock()
        processor.done = False
        scheduler.processor_agent = processor
        with mock.patch.object(settings, "USE_JOB_SCHEDULE", False), conf_vars(
            {('scheduler', 'clean_tis_without_dagrun_interval'): '0.001'}
        ):
            scheduler._run_scheduler_loop()
        ti = dr.get_task_instance(task_id=op1.task_id, session=session)
        assert ti.state == expected_task_state
        assert ti.start_date is not None
        if expected_task_state in State.finished:
            assert ti.end_date is not None
            assert ti.start_date == ti.end_date
            assert ti.duration is not None
    def test_dagrun_timeout_verify_max_active_runs(self):