### 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
assert isinstance(orm_dag.next_dagrun_data_interval_end, datetime.datetime)
        
        dr.start_date = timezone.utcnow() - datetime.timedelta(days=1)
        session.flush()
        
        self.scheduler_job.processor_agent = mock.Mock()
        self.scheduler_job.processor_agent.send_callback_to_execute = mock.Mock()
        self.scheduler_job._schedule_dag_run(dr, session)
        session.flush()
        session.refresh(dr)
        assert dr.state == State.FAILED
        session.refresh(orm_dag)
        assert isinstance(orm_dag.next_dagrun, datetime.datetime)
        assert isinstance(orm_dag.next_dagrun_data_interval_start, datetime.datetime)
        assert isinstance(orm_dag.next_dagrun_data_interval_end, datetime.datetime)
        assert isinstance(orm_dag.next_dagrun_create_after, datetime.datetime)
        expected_callback = DagCallbackRequest(
            full_filepath=dr.dag.fileloc,
            dag_id=dr.dag_id,
            is_failure_callback=True,
            run_id=dr.run_id,
            msg="timed_out",
        )
        
        self.scheduler_job.processor_agent.send_callback_to_execute.assert_called_once_with(expected_callback)
        session.rollback()
        session.close()
    def test_dagrun_timeout_fails_run(self, dag_maker):
        """
        Test if a a dagrun will be set failed if timeout, even without max_active_runs