This tests fails occasionally on mysql at least:

https://github.com/apache/airflow/pull/11555/checks?check_run_id=1260840314#step:9:1125

```
=================================== FAILURES ===================================
_____________ TestSchedulerJob.test_no_orphan_process_will_be_left _____________

self = <tests.jobs.test_scheduler_job.TestSchedulerJob testMethod=test_no_orphan_process_will_be_left>

    def test_no_orphan_process_will_be_left(self):
        empty_dir = mkdtemp()
        current_process = psutil.Process()
        old_children = current_process.children(recursive=True)
        scheduler = SchedulerJob(subdir=empty_dir,
                                 num_runs=1,
                                 executor=MockExecutor(do_update=False))
        scheduler.run()
        shutil.rmtree(empty_dir)
    
        # Remove potential noise created by previous tests.
        current_children = set(current_process.children(recursive=True)) - set(
            old_children)
>       self.assertFalse(current_children)
E       AssertionError: {psutil.Process(pid=3474, name='/usr/local/bin/', status='running', started='19:26:22')} is not false

tests/jobs/test_scheduler_job.py:871: AssertionError
```



tests/models/test_taskinstance.py
{
                        'args': [
                            'airflow',
                            'tasks',
                            'run',
                            'test_get_rendered_k8s_spec',
                            'op1',
                            '2016-01-01T00:00:00+00:00',
                        ],
                        'image': ':',
                        'name': 'base',
                        'env': [{'name': 'AIRFLOW_IS_K8S_EXECUTOR_POD', 'value': 'True'}],
                    }
                ]
            },
        }
        with create_session() as session:
            rtif = RenderedTaskInstanceFields(ti)
            session.add(rtif)
            assert rtif.k8s_pod_yaml == expected_pod_spec
        
        with DAG('test_get_rendered_k8s_spec', start_date=DEFAULT_DATE):
            new_task = BashOperator(task_id='op1', bash_command="{{ task.task_id }}")
        new_ti = TI(task=new_task, execution_date=DEFAULT_DATE)
        pod_spec = new_ti.get_rendered_k8s_spec()
        assert expected_pod_spec == pod_spec
        
        with create_session() as session:
            session.query(RenderedTaskInstanceFields).delete()
    def validate_ti_states(self, dag_run, ti_state_mapping, error_message):