lib: remove unused msg parameter in debug_agent

Removed the msg parameter in the Client function
of _debug_agent.js, because it is unused.

PR-URL: nodejs#11833
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Jackson Tian <shyvo1987@gmail.com>

lib/_debug_agent.js

@@ -107,7 +107,7 @@ function Client(agent, socket) {
 }
 util.inherits(Client, Transform);
 
-Client.prototype.destroy = function destroy(msg) {
+Client.prototype.destroy = function destroy() {
   this.socket.destroy();
 
   this.emit('close');