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
dag_id = 'test_generate_command_default_param'
        task_id = 'task'
        assert_command = ['airflow', 'tasks', 'run', dag_id, task_id, DEFAULT_DATE.isoformat()]
        generate_command = TI.generate_command(dag_id=dag_id, task_id=task_id, execution_date=DEFAULT_DATE)
        assert assert_command == generate_command
    def test_generate_command_specific_param(self):
        dag_id = 'test_generate_command_specific_param'
        task_id = 'task'
        assert_command = [
            'airflow',
            'tasks',
            'run',
            dag_id,
            task_id,
            DEFAULT_DATE.isoformat(),
            '--mark-success',
        ]
        generate_command = TI.generate_command(
            dag_id=dag_id, task_id=task_id, execution_date=DEFAULT_DATE, mark_success=True
        )
        assert assert_command == generate_command
    def test_get_rendered_template_fields(self):