### 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
([23, 13, 13, 13], 1, 1, "1d", "@once", "no_structure"),
            ([23, 13, 13, 13], 1, 1, "1d", "@once", "linear"),
            ([23, 24, 26, 28], 1, 1, "1d", "30m", "no_structure"),
            ([23, 24, 26, 28], 1, 1, "1d", "30m", "linear"),
            ([23, 24, 26, 28], 1, 1, "1d", "30m", "binary_tree"),
            ([23, 24, 26, 28], 1, 1, "1d", "30m", "star"),
            ([23, 24, 26, 28], 1, 1, "1d", "30m", "grid"),
            
            ([10, 10, 10, 10], 1, 5, "1d", "None", "no_structure"),
            ([10, 10, 10, 10], 1, 5, "1d", "None", "linear"),
            ([23, 13, 13, 13], 1, 5, "1d", "@once", "no_structure"),
            ([24, 14, 14, 14], 1, 5, "1d", "@once", "linear"),
            ([23, 24, 26, 28], 1, 5, "1d", "30m", "no_structure"),
            ([24, 26, 29, 32], 1, 5, "1d", "30m", "linear"),
            ([24, 26, 29, 32], 1, 5, "1d", "30m", "binary_tree"),
            ([24, 26, 29, 32], 1, 5, "1d", "30m", "star"),
            ([24, 26, 29, 32], 1, 5, "1d", "30m", "grid"),
            
            ([10, 10, 10, 10], 10, 10, "1d", "None", "no_structure"),
            ([10, 10, 10, 10], 10, 10, "1d", "None", "linear"),
            ([95, 28, 28, 28], 10, 10, "1d", "@once", "no_structure"),
            ([105, 41, 41, 41], 10, 10, "1d", "@once", "linear"),
            ([95, 99, 99, 99], 10, 10, "1d", "30m", "no_structure"),
            ([105, 125, 125, 125], 10, 10, "1d", "30m", "linear"),
            ([105, 119, 119, 119], 10, 10, "1d", "30m", "binary_tree"),
            ([105, 119, 119, 119], 10, 10, "1d", "30m", "star"),
            ([105, 119, 119, 119], 10, 10, "1d", "30m", "grid"),
        ],
    )
    def test_process_dags_queries_count(