

**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
of this task fails. a context dictionary is passed as a single
        parameter to this function. Context contains references to related
        objects to the task instance and is documented under the macros
        section of the API.
    :type on_failure_callback: TaskStateChangeCallback
    :param on_execute_callback: much like the ``on_failure_callback`` except
        that it is executed right before the task is executed.
    :type on_execute_callback: TaskStateChangeCallback
    :param on_retry_callback: much like the ``on_failure_callback`` except
        that it is executed when retries occur.
    :type on_retry_callback: TaskStateChangeCallback
    :param on_success_callback: much like the ``on_failure_callback`` except
        that it is executed when the task succeeds.
    :type on_success_callback: TaskStateChangeCallback
    :param trigger_rule: defines the rule by which dependencies are applied
        for the task to get triggered. Options are:
        ``{ all_success | all_failed | all_done | one_success |
        one_failed | none_failed | none_failed_or_skipped | none_skipped | dummy}``
        default is ``all_success``. Options can be set as string or
        using the constants defined in the static class
        ``airflow.utils.TriggerRule``
    :type trigger_rule: str
    :param resources: A map of resource parameter names (the argument names of the
        Resources constructor) to their values.
    :type resources: dict
    :param run_as_user: unix username to impersonate while running the task
    :type run_as_user: str
    :param task_concurrency: When set, a task will be able to limit the concurrent
        runs across execution_dates
    :type task_concurrency: int