Make test_runner use separate logger with default INFO

previous change to use logging from torchtitan caused stdout not
to show up.

ghstack-source-id: 30a77c59ba68043ffa844be0443d5351d9584fab
Pull Request resolved: #352

test_runner.py

@@ -5,13 +5,15 @@
 # LICENSE file in the root directory of this source tree.
 
 import argparse
+import logging
 import os
 import subprocess
 from collections import defaultdict
 from dataclasses import dataclass
 from typing import Sequence
 
-from torchtitan.logging_utils import logger
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
 
 try:
     import tomllib