Assign service pointer for cloned tee DCBs

When a cloned DCB is created, the service pointer is not copied and it
needs to be manually set in the newSession entry point. This most likely
due to the fact that the cloned DCB always has a different service and it
is not possible to deduce it.

Another option would be to pass the target service as a parameter but the
whole DCB cloning process could use with a rewrite so any modifications
beyond the required minimum are wasteful.

server/modules/filter/tee/tee.c

@@ -493,6 +493,8 @@ newSession(MXS_FILTER *instance, MXS_SESSION *session)
                 goto retblock;
             }
 
+            dcb->service = my_instance->service;
+
             if ((ses = session_alloc(my_instance->service, dcb)) == NULL)
             {
                 dcb_close(dcb);