test: use reserved .invalid TLD for invalid address in test

RFC 2606 reserves ithe .invalid top-level-domain for use in "domain
names that are sure to be invalid and which it is obvious at a glance
are invalid." Replace `dne.example.com` which actually isn't guaranteed
to not exist. (example.com is for examples, but at least one address
does in fact exist in that TLD.)

PR-URL: #30545
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: Trott

test/internet/test-dgram-send-cb-quelches-error.js

@@ -24,7 +24,7 @@ function callbackOnly(err) {
   assert.ok(err);
   socket.removeListener('error', onEvent);
   socket.on('error', mustCall(onError));
-  socket.send(buffer, 0, buffer.length, 100, 'dne.example.com');
+  socket.send(buffer, 0, buffer.length, 100, 'dne.invalid');
 }
 
 function onEvent(err) {