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
['one_success', 5, 0, 0, 0, 5, True, None, True],
            ['one_success', 2, 0, 0, 0, 2, True, None, True],
            ['one_success', 2, 0, 1, 0, 3, True, None, True],
            ['one_success', 2, 1, 0, 0, 3, True, None, True],
            #
            
            #
            ['all_failed', 5, 0, 0, 0, 5, True, State.SKIPPED, False],
            ['all_failed', 0, 0, 5, 0, 5, True, None, True],
            ['all_failed', 2, 0, 0, 0, 2, True, State.SKIPPED, False],
            ['all_failed', 2, 0, 1, 0, 3, True, State.SKIPPED, False],
            ['all_failed', 2, 1, 0, 0, 3, True, State.SKIPPED, False],
            #
            
            #
            ['one_failed', 5, 0, 0, 0, 0, True, None, False],
            ['one_failed', 2, 0, 0, 0, 0, True, None, False],
            ['one_failed', 2, 0, 1, 0, 0, True, None, True],
            ['one_failed', 2, 1, 0, 0, 3, True, None, False],
            ['one_failed', 2, 3, 0, 0, 5, True, State.SKIPPED, False],
            #
            
            #
            ['all_done', 5, 0, 0, 0, 5, True, None, True],
            ['all_done', 2, 0, 0, 0, 2, True, None, False],
            ['all_done', 2, 0, 1, 0, 3, True, None, False],
            ['all_done', 2, 1, 0, 0, 3, True, None, False],
        ]
    )
    def test_check_task_dependencies(