**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/operators/livy.py
#
#
"""This module contains the Apache Livy operator."""
from time import sleep
from typing import Any, Dict, Optional, Sequence, Union
from airflow.exceptions import AirflowException
from airflow.models import BaseOperator
from airflow.providers.apache.livy.hooks.livy import BatchState, LivyHook
class LivyOperator(BaseOperator):
    """
    This operator wraps the Apache Livy batch REST API, allowing to submit a Spark
    application to the underlying cluster.
    :param file: path of the file containing the application to execute (required).
    :type file: str
    :param class_name: name of the application Java/Spark main class.
    :type class_name: str
    :param args: application command line arguments.
    :type args: list
    :param jars: jars to be used in this sessions.
    :type jars: list
    :param py_files: python files to be used in this session.
    :type py_files: list
    :param files: files to be used in this session.
    :type files: list
    :param driver_memory: amount of memory to use for the driver process.
    :type driver_memory: str