**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
return result
    def post_batch(self, *args: Any, **kwargs: Any) -> Any:
        """
        Perform request to submit batch
        :return: batch session id
        :rtype: int
        """
        batch_submit_body = json.dumps(self.build_post_batch_body(*args, **kwargs))
        if self.base_url is None:
            
            self.get_conn()
        self.log.info("Submitting job %s to %s", batch_submit_body, self.base_url)
        response = self.run_method(
            method='POST', endpoint='/batches', data=batch_submit_body, headers=self.extra_headers
        )
        self.log.debug("Got response: %s", response.text)
        try:
            response.raise_for_status()
        except requests.exceptions.HTTPError as err:
            raise AirflowException(
                "Could not submit batch. Status code: {}. Message: '{}'".format(
                    err.response.status_code, err.response.text
                )
            )
        batch_id = self._parse_post_response(response.json())
        if batch_id is None:
            raise AirflowException("Unable to parse the batch session id")
        self.log.info("Batch submitted with session id: %d", batch_id)
        return batch_id
    def get_batch(self, session_id: Union[int, str]) -> Any: