don't run cuda install tasks unless during build

Author: sjpb

ansible/extras.yml

@@ -26,6 +26,7 @@
   tasks:
     - import_role:
         name: cuda
+      tasks_from: "{{ 'runtime.yml' if appliances_mode == 'configure' else 'install.yml' }}"
 
 - name: Persist hostkeys across rebuilds
   # Must be after filesystems.yml (for storage)