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/models/test_taskinstance.py
email='test@test.test',
            on_success_callback=callback_wrapper.success_handler,
            dag=dag,
        )
        ti = TI(task=task, execution_date=datetime.datetime.now())
        ti.state = State.RUNNING
        session = settings.Session()
        session.merge(ti)
        dag.create_dagrun(
            execution_date=ti.execution_date,
            state=State.RUNNING,
            run_type=DagRunType.SCHEDULED,
            session=session,
        )
        session.commit()
        callback_wrapper.wrap_task_instance(ti)
        ti._run_raw_task()
        ti._run_finished_callback()
        assert callback_wrapper.callback_ran
        assert callback_wrapper.task_state_in_callback == State.SUCCESS
        ti.refresh_from_db()
        assert ti.state == State.SUCCESS
    @staticmethod
    def _test_previous_dates_setup(
        schedule_interval: Union[str, datetime.timedelta, None], catchup: bool, scenario: List[str]
    ) -> list:
        dag_id = 'test_previous_dates'
        dag = models.DAG(dag_id=dag_id, schedule_interval=schedule_interval, catchup=catchup)
        task = DummyOperator(task_id='task', dag=dag, start_date=DEFAULT_DATE)
        def get_test_ti(session, execution_date: pendulum.DateTime, state: str) -> TI: