Call on_add before distance to properly initialize lbp

In DC aware lbp when local_dc is not provided we set it in
on_add and it needs to be initialized for distance to give
proper results.

Author: sylwiaszunejko

cassandra/cluster.py

@@ -2016,14 +2016,14 @@ def on_add(self, host, refresh_nodes=True):
 
         log.debug("Handling new host %r and notifying listeners", host)
 
+        self.profile_manager.on_add(host)
+        self.control_connection.on_add(host, refresh_nodes)
+
         distance = self.profile_manager.distance(host)
         if distance != HostDistance.IGNORED:
             self._prepare_all_queries(host)
             log.debug("Done preparing queries for new host %r", host)
 
-        self.profile_manager.on_add(host)
-        self.control_connection.on_add(host, refresh_nodes)
-
         if distance == HostDistance.IGNORED:
             log.debug("Not adding connection pool for new host %r because the "
                       "load balancing policy has marked it as IGNORED", host)