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
"""
        DagRuns with one failed and one successful root task -> SUCCESS
        """
        self.evaluate_dagrun(
            dag_id='test_dagrun_states_success',
            expected_task_states={
                'test_dagrun_fail': State.FAILED,
                'test_dagrun_succeed': State.SUCCESS,
            },
            dagrun_state=State.SUCCESS,
        )
    def test_dagrun_root_fail(self):
        """
        DagRuns with one successful and one failed root task -> FAILED
        """
        self.evaluate_dagrun(
            dag_id='test_dagrun_states_root_fail',
            expected_task_states={
                'test_dagrun_succeed': State.SUCCESS,
                'test_dagrun_fail': State.FAILED,
            },
            dagrun_state=State.FAILED,
        )
    def test_dagrun_root_fail_unfinished(self):