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
#
#
import logging
import re
import traceback
from collections import Counter
from contextlib import contextmanager
from sqlalchemy import event
import airflow.settings
log = logging.getLogger(__name__)
def assert_equal_ignore_multiple_spaces(case, first, second, msg=None):
    def _trim(s):
        return re.sub(r"\s+", " ", s.strip())
    return case.assertEqual(_trim(first), _trim(second), msg)
class CountQueries:
    """
    Counts the number of queries sent to Airflow Database in a given context.
    Does not support multiple processes. When a new process is started in context, its queries will
    not be included.
    """
    def __init__(self):
        self.result = Counter()
    def __enter__(self):
        event.listen(airflow.settings.engine, "after_cursor_execute", self.after_cursor_execute)
        return self.result
    def __exit__(self, type_, value, tb):
        event.remove(airflow.settings.engine, "after_cursor_execute", self.after_cursor_execute)
        log.debug("Queries count: %d", sum(self.result.values()))
    def after_cursor_execute(self, *args, **kwargs):