Send HTTP pushes direct to http-priv rather than via clouldflare

(This is a heinous hack that ought to be made more generic and pushed back to develop)

synapse/push/httppusher.py

@@ -329,7 +329,12 @@ def dispatch_push(self, event, tweaks, badge):
         if not notification_dict:
             defer.returnValue([])
         try:
-            resp = yield self.http_client.post_json_get_json(self.url, notification_dict)
+            url = self.url.replace(
+                "https://matrix.org/_matrix/push/v1/notify",
+                "http://http-priv.matrix.org/_matrix/push/v1/notify",
+            )
+
+            resp = yield self.http_client.post_json_get_json(url, notification_dict)
         except Exception:
             logger.warn(
                 "Failed to push event %s to %s",