nixbld: do not log refused connections

Happen all the time and spam the kernel log.

nixbld-etc-nixos/configuration.nix

@@ -92,6 +92,7 @@ in
       allowedTCPPorts = [ 53 80 443 2222 7402 ];
       allowedUDPPorts = [ 53 67 500 4500 ];
       trustedInterfaces = [ netifLan ];
+      logRefusedConnections = false;
     };
     useDHCP = false;
     interfaces."${netifWan}".useDHCP = true;  # PCCW - always wants active DHCP lease or cuts you off