

**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
config, config_sources, display_source, raw, section, source_name
    ):
        sect = config_sources.setdefault(section, OrderedDict())
        for (k, val) in config.items(section=section, raw=raw):
            if display_source:
                val = (val, source_name)
            sect[k] = val
    def load_test_config(self):
        """
        Load the unit test configuration.
        Note: this is not reversible.
        """
        
        for section in self.sections():
            self.remove_section(section)
        
        path = _default_config_file_path('default_test.cfg')
        log.info("Reading default test configuration from %s", path)
        self.read_string(_parameterized_config_from_template('default_test.cfg'))
        
        log.info("Reading test configuration from %s", TEST_CONFIG_FILE)
        self.read(TEST_CONFIG_FILE)
    @staticmethod
    def _warn_deprecate(section, key, deprecated_section, deprecated_name):