### 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
"""
        Integration test of the scheduler not accidentally resetting
        the try_numbers for a task
        """
        dag = self.dagbag.get_dag('test_retry_handling_job')
        dag_task1 = dag.get_task("test_retry_handling_op")
        dag.clear()
        self.scheduler_job = SchedulerJob(dag_id=dag.dag_id, num_runs=1)
        self.scheduler_job.heartrate = 0
        self.scheduler_job.run()
        session = settings.Session()
        ti = (
            session.query(TaskInstance)
            .filter(TaskInstance.dag_id == dag.dag_id, TaskInstance.task_id == dag_task1.task_id)
            .first()
        )
        
        assert ti.try_number == 2
        assert ti.state == State.UP_FOR_RETRY
    def test_dag_get_active_runs(self, dag_maker):