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
"""
        Test that Operator links are not loaded inside the Scheduling Loop (that does not include
        DagFileProcessorProcess) especially the critical loop of the Scheduler.
        This is to avoid running User code in the Scheduler and prevent any deadlocks
        """
        dag = DAG(dag_id='test_extra_operator_links_not_loaded_in_scheduler', start_date=DEFAULT_DATE)
        
        _ = CustomOperator(task_id='custom_task', dag=dag)
        dagbag = DagBag(
            dag_folder=os.path.join(settings.DAGS_FOLDER, "no_dags.py"),
            include_examples=False,
            read_dags_from_db=True,
        )
        dagbag.bag_dag(dag=dag, root_dag=dag)
        dagbag.sync_to_db()
        
        s_dag_1 = dagbag.get_dag(dag.dag_id)
        custom_task = s_dag_1.task_dict['custom_task']
        
        assert custom_task.operator_extra_links
        scheduler = SchedulerJob(executor=self.null_exec)
        scheduler.processor_agent = mock.MagicMock()
        scheduler._run_scheduler_loop()
        
        s_dag_2 = scheduler.dagbag.get_dag(dag.dag_id)
        custom_task = s_dag_2.task_dict['custom_task']
        
        assert not custom_task.operator_extra_links
    def test_scheduler_create_dag_runs_does_not_raise_error(self):