Remove no longer used util.listen function

py-spy dump --pid <pid> makes for a nice alternative we don't have to maintain. Plus it can show local variables.

frigate/util/services.py

@@ -7,7 +7,6 @@ import os
 import re
 import signal
 import subprocess as sp
-import traceback
 from typing import Optional
 
 import cv2
@@ -36,14 +35,6 @@ def restart_frigate():
         os.kill(os.getpid(), signal.SIGINT)
 
 
-def print_stack(sig, frame):
-    traceback.print_stack(frame)
-
-
-def listen():
-    signal.signal(signal.SIGUSR1, print_stack)
-
-
 def get_cgroups_version() -> str:
     """Determine what version of cgroups is enabled."""