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
else:
                assert start_date is None
                assert end_date is None
                assert duration is None
@pytest.mark.usefixtures("disable_load_example")
class TestSchedulerJob(unittest.TestCase):
    def setUp(self):
        clear_db_runs()
        clear_db_pools()
        clear_db_dags()
        clear_db_sla_miss()
        clear_db_import_errors()
        
        
        self.null_exec = MockExecutor()
        self.patcher = patch('airflow.utils.dag_processing.SerializedDagModel.remove_deleted_dags')
        
        self.patcher_dag_code = patch.object(settings, "STORE_DAG_CODE", False)
        self.patcher.start()
        self.patcher_dag_code.start()
    def tearDown(self):
        self.patcher.stop()
        self.patcher_dag_code.stop()
    @classmethod
    def setUpClass(cls):
        
        non_serialized_dagbag = DagBag(read_dags_from_db=False, include_examples=False)
        non_serialized_dagbag.sync_to_db()
        cls.dagbag = DagBag(read_dags_from_db=True)
    def test_is_alive(self):