### Apache Airflow version

2.2.0 (latest released)

### Operating System

Mac

### Versions of Apache Airflow Providers

_No response_

### Deployment

Other Docker-based deployment

### Deployment details

_No response_

### What happened

Getting an exception when returning None from next_dagrun_info in a custom timetable. The timetable protocol says that when None is returned a DagRun will not happen but right now it throws an exception.

Exception:
```
Traceback (most recent call last):
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/jobs/scheduler_job.py", line 623, in _execute
    self._run_scheduler_loop()
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/jobs/scheduler_job.py", line 704, in _run_scheduler_loop
    num_queued_tis = self._do_scheduling(session)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/jobs/scheduler_job.py", line 787, in _do_scheduling
    callback_to_run = self._schedule_dag_run(dag_run, session)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/jobs/scheduler_job.py", line 1039, in _schedule_dag_run
    self._update_dag_next_dagruns(dag, dag_model, active_runs)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/jobs/scheduler_job.py", line 930, in _update_dag_next_dagruns
    data_interval = dag.get_next_data_interval(dag_model)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/models/dag.py", line 629, in get_next_data_interval
    return self.infer_automated_data_interval(dag_model.next_dagrun)
  File "/home/airflow/.local/lib/python3.9/site-packages/airflow/models/dag.py", line 671, in infer_automated_data_interval
    raise ValueError(f"Not a valid timetable: {self.timetable!r}")
ValueError: Not a valid timetable: <my_timetables.workday_timetable.WorkdayTimetable object at 0x7f42b1f02430>
```

### What you expected to happen

DagRun to not happen.

### How to reproduce

Create a custom timetable and return None in next_dagrun_info after a few DagRuns are created by that timetable

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

tests/models/test_dag.py
with DAG("test_dag", start_date=DEFAULT_DATE) as dag:
            op1 = DummyOperator(task_id='t1')
            op2 = DummyOperator(task_id='t2')
            op3 = DummyOperator(task_id='t3')
            op1 >> op2
            op2 >> op3
        sub_dag = dag.partial_subset('t2', include_upstream=True, include_downstream=False)
        assert id(sub_dag.task_dict['t1'].downstream_list[0].dag) == id(sub_dag)
        
        assert 't3' not in sub_dag._task_group.used_group_ids
    def test_schedule_dag_no_previous_runs(self):
        """
        Tests scheduling a dag with no previous runs
        """
        dag_id = "test_schedule_dag_no_previous_runs"
        dag = DAG(dag_id=dag_id)
        dag.add_task(BaseOperator(task_id="faketastic", owner='Also fake', start_date=TEST_DATE))
        dag_run = dag.create_dagrun(
            run_type=DagRunType.SCHEDULED,
            execution_date=TEST_DATE,
            state=State.RUNNING,
        )
        assert dag_run is not None
        assert dag.dag_id == dag_run.dag_id
        assert dag_run.run_id is not None
        assert '' != dag_run.run_id
        assert (
            TEST_DATE == dag_run.execution_date