We'll create fresh WordPress site with ROB (rat out blocker) installed. You have 20 minutes to test the plugin after that site we'll be deleted.
With this simple plugin you can restrict extra external requests made with internal wordpress WP_Http class.
Just put in filter rules field what you wish to restrict. One url part or url regex per line.
By default plugin return WP_Error answer for restricted requests. But you can put in response your custom response data.