### 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
clear_db_runs()
        clear_db_pools()
        clear_db_dags()
        clear_db_sla_miss()
        clear_db_import_errors()
        clear_db_jobs()
        clear_db_serialized_dags()
    @pytest.fixture(autouse=True)
    def per_test(self) -> Generator:
        self.clean_db()
        yield
        if self.scheduler_job and self.scheduler_job.processor_agent:
            self.scheduler_job.processor_agent.end()
            self.scheduler_job = None
        self.clean_db()
    @pytest.mark.parametrize(
        "expected_query_count, dag_count, task_count",
        [
            (20, 1, 1),  
            (20, 1, 5),  
            (83, 10, 10),  
        ],
    )
    def test_execute_queries_count_with_harvested_dags(self, expected_query_count, dag_count, task_count):