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
called = False
        def on_execute_callable(context):
            nonlocal called
            called = True
            assert context['dag_run'].dag_id == 'test_dagrun_execute_callback'
        dag = DAG(
            'test_execute_callback',
            start_date=DEFAULT_DATE,
            end_date=DEFAULT_DATE + datetime.timedelta(days=10),
        )
        task = DummyOperator(
            task_id='op', email='test@test.test', on_execute_callback=on_execute_callable, dag=dag
        )
        ti = TI(task=task, execution_date=datetime.datetime.now())
        ti.state = State.RUNNING
        session = settings.Session()
        dag.create_dagrun(
            execution_date=ti.execution_date,
            state=State.RUNNING,
            run_type=DagRunType.SCHEDULED,
            session=session,
        )
        session.merge(ti)
        session.commit()
        ti._run_raw_task()
        assert called
        ti.refresh_from_db()
        assert ti.state == State.SUCCESS
    def test_handle_failure(self):