Properly tear down zun-api at wsgi mode

If wsgi mode is enabled, zun-api should be disabled in apache,
otherwise shutdown the process as before.

Change-Id: I33979a5454a3d68415fcfff01e9de6e99f8b31d6

devstack/lib/zun

@@ -462,9 +462,14 @@ function stop_zun {
     if is_service_enabled zun-etcd; then
         stop_zun_etcd
     fi
-    for serv in zun-api zun-compute; do
-        stop_process $serv
-    done
+
+    if [ "$ZUN_USE_MOD_WSGI" == "True" ]; then
+        disable_apache_site zun
+        restart_apache_server
+    else
+        stop_process zun-api
+    fi
+    stop_process zun-compute
 }
 
 # Restore xtrace