

**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
"""Returns True if the Operator has been assigned to a DAG."""
        return getattr(self, '_dag', None) is not None
    @property
    def dag_id(self) -> str:
        """Returns dag id if it has one or an adhoc + owner"""
        if self.has_dag():
            return self.dag.dag_id
        else:
            return 'adhoc_' + self.owner
    deps: Iterable[BaseTIDep] = frozenset(
        {
            NotInRetryPeriodDep(),
            PrevDagrunDep(),
            TriggerRuleDep(),
            NotPreviouslySkippedDep(),
        }
    )
    """
    Returns the set of dependencies for the operator. These differ from execution
    context dependencies in that they are specific to tasks and can be
    extended/overridden by subclasses.
    """
    def prepare_for_execution(self) -> "BaseOperator":