

**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/configuration.py
"""Get path to unittests.cfg"""
    if 'AIRFLOW_TEST_CONFIG' not in os.environ:
        return os.path.join(airflow_home, 'unittests.cfg')
    return expand_env_var(os.environ['AIRFLOW_TEST_CONFIG'])
def _generate_fernet_key():
    from cryptography.fernet import Fernet
    return Fernet.generate_key().decode()
def initialize_config():
    """
    Load the Airflow config files.
    Called for you automatically as part of the Airflow boot process.
    """
    global FERNET_KEY, AIRFLOW_HOME
    default_config = _parameterized_config_from_template('default_airflow.cfg')
    conf = AirflowConfigParser(default_config=default_config)
    if conf.getboolean('core', 'unit_test_mode'):
        
        if not os.path.isfile(TEST_CONFIG_FILE):
            from cryptography.fernet import Fernet
            log.info('Creating new Airflow config file for unit tests in: %s', TEST_CONFIG_FILE)
            pathlib.Path(AIRFLOW_HOME).mkdir(parents=True, exist_ok=True)
            FERNET_KEY = Fernet.generate_key().decode()
            with open(TEST_CONFIG_FILE, 'w') as file:
                cfg = _parameterized_config_from_template('default_test.cfg')
                file.write(cfg)
        conf.load_test_config()
    else:
        
        if not os.path.isfile(AIRFLOW_CONFIG):