### Body

The `test_no_orphan_process_will_be_left` in `TestSchedulerJob` is really flaky.

Before we know how to fix it, I will quarantine it:

https://github.com/apache/airflow/pull/18691/checks?check_run_id=3811660138

```
  =================================== FAILURES ===================================
  _____________ TestSchedulerJob.test_no_orphan_process_will_be_left _____________
  
  self = <tests.jobs.test_scheduler_job.TestSchedulerJob object at 0x7fc2f91d2ac8>
  
      def test_no_orphan_process_will_be_left(self):
          empty_dir = mkdtemp()
          current_process = psutil.Process()
          old_children = current_process.children(recursive=True)
          self.scheduler_job = SchedulerJob(
              subdir=empty_dir, num_runs=1, executor=MockExecutor(do_update=False)
          )
          self.scheduler_job.run()
          shutil.rmtree(empty_dir)
      
          # Remove potential noise created by previous tests.
          current_children = set(current_process.children(recursive=True)) - set(old_children)
  >       assert not current_children
  E       AssertionError: assert not {psutil.Process(pid=2895, name='pytest', status='running', started='06:53:45')}
  
```

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
tests/jobs/test_scheduler_job.py
dag_id = 'SchedulerJobTest.test_enqueue_task_instances_with_queued_state'
        task_id_1 = 'dummy'
        session = settings.Session()
        with dag_maker(dag_id=dag_id, start_date=DEFAULT_DATE, session=session):
            task1 = DummyOperator(task_id=task_id_1)
        self.scheduler_job = SchedulerJob(subdir=os.devnull)
        dr1 = dag_maker.create_dagrun()
        ti1 = dr1.get_task_instance(task1.task_id, session)
        with patch.object(BaseExecutor, 'queue_command') as mock_queue_command:
            self.scheduler_job._enqueue_task_instances_with_queued_state([ti1])
        assert mock_queue_command.called
        session.rollback()
    @pytest.mark.parametrize("state", [State.FAILED, State.SUCCESS])
    def test_enqueue_task_instances_sets_ti_state_to_None_if_dagrun_in_finish_state(self, state, dag_maker):