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/test_utils/asserts.py
stack = [
            f
            for f in traceback.extract_stack()
            if 'sqlalchemy' not in f.filename
            and __file__ != f.filename
            and ('session.py' not in f.filename and f.name != 'wrapper')
        ]
        stack_info = ">".join([f"{f.filename.rpartition('/')[-1]}:{f.name}" for f in stack][-3:])
        lineno = stack[-1].lineno
        self.result[f"{stack_info}:{lineno}"] += 1
count_queries = CountQueries  
@contextmanager
def assert_queries_count(expected_count, message_fmt=None):
    with count_queries() as result:
        yield None
    count = sum(result.values())
    if expected_count != count:
        message_fmt = (
            message_fmt
            or "The expected number of db queries is {expected_count}. "
            "The current number is {current_count}.\n\n"
            "Recorded query locations:"
        )
        message = message_fmt.format(current_count=count, expected_count=expected_count)
        for location, count in result.items():
            message += f'\n\t{location}:\t{count}'
        raise AssertionError(message)