### 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/cli/commands/dag_command.py
start_date=args.start_date,
                end_date=args.end_date,
                mark_success=args.mark_success,
                local=args.local,
                donot_pickle=(args.donot_pickle or conf.getboolean('core', 'donot_pickle')),
                ignore_first_depends_on_past=args.ignore_first_depends_on_past,
                ignore_task_deps=args.ignore_dependencies,
                pool=args.pool,
                delay_on_limit_secs=args.delay_on_limit,
                verbose=args.verbose,
                conf=run_conf,
                rerun_failed_tasks=args.rerun_failed_tasks,
                run_backwards=args.run_backwards,
            )
        except ValueError as vr:
            print(str(vr))
            sys.exit(1)
@cli_utils.action_logging
def dag_trigger(args):
    """Creates a dag run for the specified dag"""
    api_client = get_current_api_client()
    try:
        message = api_client.trigger_dag(
            dag_id=args.dag_id, run_id=args.run_id, conf=args.conf, execution_date=args.exec_date
        )
        print(message)
    except OSError as err:
        raise AirflowException(err)
@cli_utils.action_logging
def dag_delete(args):