### Apache Airflow version

2.2.0b2 (beta snapshot)

### Operating System

ubuntu 20.04

### Versions of Apache Airflow Providers

n/a

### Deployment

Virtualenv installation

### Deployment details

pip install /path/to/airflow/src

### What happened

Given any DAG initialized with: `schedule_interval=None`

Run `airflow dags test mydagname $(date +%Y-%m-%d)` and get an error:

```
INFO - No run dates were found for the given dates and dag interval.
```

This behavior changed in https://github.com/apache/airflow/pull/15397, it used to trigger a backfill dagrun at the given date.

### What you expected to happen

I expected a backfill dagrun with the given date, regardless of whether it fit into the `schedule_interval`.

If AIP-39 made that an unrealistic expectation, then I'd hope for some way to define unscheduled dags which can still be tested from the command line (which, so far as I know, is the fastest way to iterate on a DAG.).

As it is, I keep changing `schedule_interval` back and forth depending on whether I want to iterate via `astro dev start` (which tolerates `None` but does superfluous work if the dag is scheduled) or via `airflow dags test ...` (which doesn't tolerate `None`).

### How to reproduce

Initialize a DAG with: `schedule_interval=None` and run it via `airflow dags test mydagname $(date +%Y-%m-%d)`

### 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)

airflow/models/dag.py
)
        if orientation in ORIENTATION_PRESETS:
            self.orientation = orientation
        else:
            raise AirflowException(
                f'Invalid values of dag.orientation: only support '
                f'{ORIENTATION_PRESETS}, but get {orientation}'
            )
        self.catchup = catchup
        self.is_subdag = False  
        self.partial = False
        self.on_success_callback = on_success_callback
        self.on_failure_callback = on_failure_callback
        
        
        
        self.edge_info: Dict[str, Dict[str, EdgeInfoType]] = {}
        
        
        self.has_on_success_callback = self.on_success_callback is not None
        self.has_on_failure_callback = self.on_failure_callback is not None
        self.doc_md = doc_md
        self._access_control = DAG._upgrade_outdated_dag_access_control(access_control)
        self.is_paused_upon_creation = is_paused_upon_creation
        self.jinja_environment_kwargs = jinja_environment_kwargs
        self.render_template_as_native_obj = render_template_as_native_obj
        self.tags = tags
        self._task_group = TaskGroup.create_root(self)
        self.validate_schedule_and_params()
    def __repr__(self):