

**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
:param executor_config: Additional task-level configuration parameters that are
        interpreted by a specific executor. Parameters are namespaced by the name of
        executor.
        **Example**: to run this task in a specific docker container through
        the KubernetesExecutor ::
            MyOperator(...,
                executor_config={
                    "KubernetesExecutor":
                        {"image": "myCustomDockerImage"}
                }
            )
    :type executor_config: dict
    :param do_xcom_push: if True, an XCom is pushed containing the Operator's
        result
    :type do_xcom_push: bool
    """
    
    template_fields: Iterable[str] = ()
    
    template_ext: Iterable[str] = ()
    
    template_fields_renderers: Dict[str, str] = {}
    
    ui_color = '#fff'  
    ui_fgcolor = '#000'  
    pool = ""  
    
    _base_operator_shallow_copy_attrs: Tuple[str, ...] = (
        'user_defined_macros',
        'user_defined_filters',