[batch] silence instance logs (#14243)

`oldwarn` is somehow `None` which spams us with instance log errors. We
can revisit the warning level in a PR if this is really important.

https://cloudlogging.app.goo.gl/VmUohrJSNo6EjsK56

batch/batch/worker/worker.py

@@ -14,7 +14,6 @@
 import tempfile
 import traceback
 import uuid
-import warnings
 from collections import defaultdict
 from contextlib import AsyncExitStack, ExitStack
 from typing import (
@@ -95,19 +94,6 @@
 with open('/subdomains.txt', 'r', encoding='utf-8') as subdomains_file:
     HAIL_SERVICES = [line.rstrip() for line in subdomains_file.readlines()]
 
-oldwarn = warnings.warn
-
-
-def deeper_stack_level_warn(*args, **kwargs):
-    if 'stacklevel' in kwargs:
-        kwargs['stacklevel'] = max(kwargs['stacklevel'], 5)
-    else:
-        kwargs['stacklevel'] = 5
-    return oldwarn(*args, **kwargs)
-
-
-warnings.warn = deeper_stack_level_warn
-
 
 class BatchWorkerAccessLogger(AccessLogger):
     def __init__(self, logger: logging.Logger, log_format: str):