### 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
self,
        dag: DAG,
        most_recent_dag_run: Union[None, datetime, DataInterval],
    ) -> None:
        """
        Calculate ``next_dagrun`` and `next_dagrun_create_after``
        :param dag: The DAG object
        :param most_recent_dag_run: DateTime of most recent run of this dag, or none if not yet scheduled.
        """
        if isinstance(most_recent_dag_run, datetime):
            warnings.warn(
                "Passing a datetime to `DagModel.calculate_dagrun_date_fields` is deprecated. "
                "Provide a data interval instead.",
                DeprecationWarning,
                stacklevel=2,
            )
            most_recent_data_interval = dag.infer_automated_data_interval(most_recent_dag_run)
        else:
            most_recent_data_interval = most_recent_dag_run
        next_dagrun_info = dag.next_dagrun_info(most_recent_data_interval)
        if next_dagrun_info is None:
            self.next_dagrun_data_interval = self.next_dagrun = self.next_dagrun_create_after = None
        else:
            self.next_dagrun_data_interval = next_dagrun_info.data_interval
            self.next_dagrun = next_dagrun_info.logical_date
            self.next_dagrun_create_after = next_dagrun_info.run_after
        log.info("Setting next_dagrun for %s to %s", dag.dag_id, self.next_dagrun)
def dag(*dag_args, **dag_kwargs):