test: fix test-dns.js flakiness

Use empty string instead of `www.google.com` for tests where we are just
doing parameter evaluation. This will avoid DNS lookups which appear to
be causing flakiness on Raspberry Pi devices in CI.
PR-URL: #5996Fixes: #5554
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: Trott

test/parallel/test-dns.js

@@ -1,8 +1,8 @@
 'use strict';
 require('../common');
-varassert=require('assert');
+constassert=require('assert');
 
-vardns=require('dns');
+constdns=require('dns');
 
 varexisting=dns.getServers();
 assert(existing.length);
@@ -121,27 +121,27 @@ assert.doesNotThrow(function() {
 });
 
 assert.doesNotThrow(function(){
-dns.lookup('www.google.com',{
+dns.lookup('',{
 family: 4,
 hints: 0
 },noop);
 });
 
 assert.doesNotThrow(function(){
-dns.lookup('www.google.com',{
+dns.lookup('',{
 family: 6,
 hints: dns.ADDRCONFIG
 },noop);
 });
 
 assert.doesNotThrow(function(){
-dns.lookup('www.google.com',{
+dns.lookup('',{
 hints: dns.V4MAPPED
 },noop);
 });
 
 assert.doesNotThrow(function(){
-dns.lookup('www.google.com',{
+dns.lookup('',{
 hints: dns.ADDRCONFIG|dns.V4MAPPED
 },noop);
 });