

**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
"""
        Remove an option if it exists in config from a file or
        default config. If both of config have the same option, this removes
        the option in both configs unless remove_default=False.
        """
        if super().has_option(section, option):
            super().remove_option(section, option)
        if self.airflow_defaults.has_option(section, option) and remove_default:
            self.airflow_defaults.remove_option(section, option)
    def getsection(self, section: str) -> Optional[Dict[str, Union[str, int, float, bool]]]:
        """
        Returns the section as a dict. Values are converted to int, float, bool
        as required.
        :param section: section from the config
        :rtype: dict
        """
        if not self.has_section(section) and not self.airflow_defaults.has_section(section):
            return None
        if self.airflow_defaults.has_section(section):
            _section = OrderedDict(self.airflow_defaults.items(section))
        else:
            _section = OrderedDict()
        if self.has_section(section):
            _section.update(OrderedDict(self.items(section)))
        section_prefix = self._env_var_name(section, '')
        for env_var in sorted(os.environ.keys()):
            if env_var.startswith(section_prefix):