### 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
session=session,
                            recursion_depth=recursion_depth + 1,
                            max_recursion_depth=max_recursion_depth,
                            visited_external_tis=visited_external_tis,
                        )
                    )
        if result or as_pk_tuple:
            
            if as_pk_tuple:
                result.update(TaskInstanceKey(*cols) for cols in tis.all())
            else:
                result.update(ti.key for ti in tis.all())
            if exclude_task_ids:
                result = set(
                    filter(
                        lambda key: key.task_id not in exclude_task_ids,
                        result,
                    )
                )
        if as_pk_tuple:
            return result
        elif result:
            
            tis = tis.with_entities(TI.dag_id, TI.task_id, TI.run_id)
            tis = session.query(TI).filter(TI.filter_for_tis(result))
        elif exclude_task_ids:
            tis = tis.filter(TI.task_id.notin_(list(exclude_task_ids)))
        return tis
    @provide_session
    def set_task_instance_state(