**Description**
The Airflow logs generated by the Livy operator currently only state the status of the submitted batch. To view the logs from the job itself, one must go separately to the session logs. I think that Airflow should have the option (possibly on by default) that retrieves the session logs after the batch reaches a terminal state if a `polling_interval` has been set.

**Use case / motivation**
When debugging a task submitted via Livy, the session logs are the first place to check. For most other tasks, including SparkSubmitOperator, viewing the first-check logs can be done in the Airflow UI, but for Livy you must go externally or write a separate task to retrieve them. 

**Are you willing to submit a PR?**

I don't yet have a good sense of how challenging this will be to set up and test. I can try but if anyone else wants to go for it, don't let my attempt stop you.

**Related Issues**

None I could find

airflow/providers/apache/livy/hooks/livy.py
"""
        Delete the specified batch
        :param session_id: identifier of the batch sessions
        :type session_id: int
        :return: response body
        :rtype: dict
        """
        self._validate_session_id(session_id)
        self.log.info("Deleting batch session %d", session_id)
        response = self.run_method(method='DELETE', endpoint=f'/batches/{session_id}')
        try:
            response.raise_for_status()
        except requests.exceptions.HTTPError as err:
            self.log.warning("Got status code %d for session %d", err.response.status_code, session_id)
            raise AirflowException(
                "Could not kill the batch with session id: {}. Message: {}".format(
                    session_id, err.response.text
                )
            )
        return response.json()
    @staticmethod
    def _validate_session_id(session_id: Union[int, str]) -> None: