

**Description**

We are using a 3rd party executor which has the ability to use multiple queues, however the `default_queue` is defined under the `celery` heading and is used regardless of the executor that you are using.

See: https://github.com/apache/airflow/blob/2.0.1/airflow/models/baseoperator.py#L366

It would be nice to decouple the default_queue configuration argument away from the celery section to allow other executors to utilise this functionality with less confusion.

**Are you willing to submit a PR?**

Yep! Will open a pull request shortly


**Related Issues**

Not that I'm aware of.

airflow/cli/cli_parser.py
func = import_string(import_path)
        return func(*args, **kwargs)
    command.__name__ = name
    return command
class DefaultHelpParser(argparse.ArgumentParser):
    """CustomParser to display help message"""
    def _check_value(self, action, value):
        """Override _check_value and check conditionally added command"""
        executor = conf.get('core', 'EXECUTOR')
        if value == 'celery' and executor not in (CELERY_EXECUTOR, CELERY_KUBERNETES_EXECUTOR):
            message = f'celery subcommand works only with CeleryExecutor, your current executor: {executor}'
            raise ArgumentError(action, message)
        if value == 'kubernetes':
            try:
                import kubernetes.client  
            except ImportError:
                message = (
                    'The kubernetes subcommand requires that you pip install the kubernetes python client.'
                    "To do it, run: pip install 'apache-airflow[cncf.kubernetes]'"
                )
                raise ArgumentError(action, message)
        if action.choices is not None and value not in action.choices:
            check_legacy_command(action, value)
        super()._check_value(action, value)
    def error(self, message):
        """Override error and use print_instead of print_usage"""
        self.print_help()
        self.exit(2, f'\n{self.prog} command error: {message}, see help above.\n')
_UNSET = object()
class Arg: