### 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
mock_gaurd.reset_mock()
                return None
            def mock_send_dag_callbacks_to_processor(*args, **kwargs):
                mock_gaurd.return_value.__enter__.return_value.commit.assert_called_once()
            self.scheduler_job._send_dag_callbacks_to_processor.side_effect = (
                mock_send_dag_callbacks_to_processor
            )
            self.scheduler_job._schedule_dag_run.side_effect = mock_schedule_dag_run
            self.scheduler_job._do_scheduling(session)
        
        self.scheduler_job._send_dag_callbacks_to_processor.assert_called_once()
        
        session.rollback()
        session.close()
    @pytest.mark.parametrize("state", [State.SUCCESS, State.FAILED])
    def test_dagrun_callbacks_are_not_added_when_callbacks_are_not_defined(self, state, dag_maker):