

**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 Config option values from Secret Backend"""
        fallback_key = key + '_secret'
        
        if (section, key) in self.sensitive_config_values:
            if super().has_option(section, fallback_key):
                secrets_path = super().get(section, fallback_key)
                return _get_config_value_from_secret_backend(secrets_path)
        return None
    def get(self, section, key, **kwargs):
        section = str(section).lower()
        key = str(key).lower()
        deprecated_section, deprecated_key, _ = self.deprecated_options.get(
            (section, key), (None, None, None)
        )
        option = self._get_environment_variables(deprecated_key, deprecated_section, key, section)
        if option is not None:
            return option
        option = self._get_option_from_config_file(deprecated_key, deprecated_section, key, kwargs, section)
        if option is not None:
            return option
        option = self._get_option_from_commands(deprecated_key, deprecated_section, key, section)
        if option is not None:
            return option
        option = self._get_option_from_secrets(deprecated_key, deprecated_section, key, section)
        if option is not None:
            return option
        return self._get_option_from_default_config(section, key, **kwargs)
    def _get_option_from_default_config(self, section, key, **kwargs):