use SIGUSR1 instead of SIGQUIT to print stack traces

bubble-server/src/main/resources/packer/roles/mitmproxy/files/bubble_conn_check.py

@@ -48,7 +48,7 @@ def dumpstacks(signal, frame):
                 code.append("  %s" % (line.strip()))
     print("\n------------------------------------- stack traces ------------------------------"+"\n".join(code), file=sys.stderr, flush=True)
 
-signal.signal(signal.SIGQUIT, dumpstacks)
+signal.signal(signal.SIGUSR1, dumpstacks)
 
 
 REDIS_DNS_PREFIX = 'bubble_dns_'