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
execution_date=DEFAULT_DATE,
            start_date=DEFAULT_DATE,
            session=session,
        )
        ti1a = dr1.get_task_instance(task_id='dummy', session=session)
        ti1a.state = State.SCHEDULED
        ti1b = dr1.get_task_instance(task_id='dummy_b', session=session)
        ti1b.state = State.SUCCESS
        session.commit()
        ti2 = dr2.get_task_instance(task_id='dummy', session=session)
        ti2.state = State.SCHEDULED
        session.commit()
        ti3 = TaskInstance(dag3.get_task('dummy'), DEFAULT_DATE)
        ti3.state = State.SCHEDULED
        session.merge(ti3)
        session.commit()
        dagbag = DagBag("/dev/null", include_examples=False, read_dags_from_db=False)
        dagbag.bag_dag(dag1, root_dag=dag1)
        dagbag.bag_dag(dag2, root_dag=dag2)
        dagbag.bag_dag(dag3, root_dag=dag3)
        dagbag.sync_to_db(session)
        session.commit()
        scheduler = SchedulerJob(num_runs=0)
        scheduler.dagbag.collect_dags_from_db()
        scheduler._change_state_for_tis_without_dagrun(
            old_states=[State.SCHEDULED, State.QUEUED], new_state=State.NONE, session=session
        )
        ti1a = dr1.get_task_instance(task_id='dummy', session=session)
        ti1a.refresh_from_db(session=session)
        assert ti1a.state == State.SCHEDULED