net: inline maybeDestroy()

`maybeDestroy()` is only called from the listener of the `'end'` event.
That event is only emitted after the socket is connected (after `UV_EOF`
is read) and after `socket.readable` is set to `false`.

PR-URL: https://github.com/nodejs/node/pull/27136
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/net.js

@@ -541,19 +541,9 @@ function onReadableStreamEnd() {
     if (this.writable)
       this.end();
   }
-  maybeDestroy(this);
-}
 
-
-// Call whenever we set writable=false or readable=false
-function maybeDestroy(socket) {
-  if (!socket.readable &&
-      !socket.writable &&
-      !socket.destroyed &&
-      !socket.connecting &&
-      !socket.writableLength) {
-    socket.destroy();
-  }
+  if (!this.destroyed && !this.writable && !this.writableLength)
+    this.destroy();
 }