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
for task_id, expected_state in ti_state_mapping.items():
            task_instance = dag_run.get_task_instance(task_id=task_id)
            assert task_instance.state == expected_state, error_message
    @parameterized.expand(
        [
            (
                {('scheduler', 'schedule_after_task_execution'): 'True'},
                {'A': 'B', 'B': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.SCHEDULED, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.SUCCESS, 'C': State.SCHEDULED},
                "A -> B -> C, with fast-follow ON when A runs, B should be QUEUED. Same for B and C.",
            ),
            (
                {('scheduler', 'schedule_after_task_execution'): 'False'},
                {'A': 'B', 'B': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.NONE, 'C': State.NONE},
                None,
                "A -> B -> C, with fast-follow OFF, when A runs, B shouldn't be QUEUED.",
            ),
            (
                {('scheduler', 'schedule_after_task_execution'): 'True'},
                {'A': 'B', 'C': 'B', 'D': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE, 'D': State.NONE},