As Karim said, cross domain ajax doesn't work unless the server allows for it. In this case Google does not, BUT, there is a simple trick to get around this in many cases. Just have your local server pass the content retrieved through HTTP or HTTPS.
For example, if you were using PHP, you could:
Create the file web_root/ajax_responders/google.php with:
<?php
echo file_get_contents('http://www.google.de');
?>
And then alter your code to connect to that instead of to Google's domain directly in the javascript:
var response = $.ajax({ type: "GET",
url: "/ajax_responders/google.php",
async: false
}).responseText;
alert(response);