

**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/models/baseoperator.py
"""
        Get list of the direct relatives to the current task, upstream or
        downstream.
        """
        if upstream:
            return self.upstream_list
        else:
            return self.downstream_list
    def __repr__(self):
        return "<Task({self.task_type}): {self.task_id}>".format(self=self)
    @property
    def task_type(self) -> str:
        """@property: type of the task"""
        return self.__class__.__name__
    def add_only_new(self, item_set: Set[str], item: str) -> None:
        """Adds only new items to item set"""
        if item in item_set:
            self.log.warning('Dependency %s, %s already registered', self, item)
        else:
            item_set.add(item)
    @property
    def roots(self) -> List["BaseOperator"]:
        """Required by TaskMixin"""
        return [self]
    @property
    def leaves(self) -> List["BaseOperator"]: