Use Ubuntu minimal image as advanced guest image

Ubuntu minimal is smaller than regular cloud image.
It should works fine with less memory and boot faster than in
the gates.

Change-Id: Ie281698ecef05fd7ddf831eabd0e0121ac477709
diff --git a/devstack/plugin.sh b/devstack/plugin.sh
index 2e3ac20..42c31cd 100644
--- a/devstack/plugin.sh
+++ b/devstack/plugin.sh
@@ -6,7 +6,6 @@
 # install_neutron_tempest_plugin
 function install_neutron_tempest_plugin {
     setup_dev_lib "neutron-tempest-plugin"
-    install_customize_image_tools
 }
 
 if [[ "$1" == "stack" ]]; then
@@ -20,7 +19,7 @@
         test-config)
             echo_summary "Configuring neutron-tempest-plugin tempest options"
             configure_advanced_image
-            create_flavor_for_advance_image ntp_image_384M 384 4 1
+            create_flavor_for_advance_image $ADVANCED_INSTANCE_TYPE 256 4 1
             configure_flavor_for_advanced_image
     esac
 fi