Nova: Update MVP values to reflect removal of oslo-genconfig tool

This PS updates the Nova MVP values to reflect the removal of
the oslo-genfig tool.

Change-Id: Ibb5c2b4e97d119da138fe1ba853137f517703bcd

tools/overrides/mvp/nova.yaml

@@ -17,13 +17,7 @@ ceph:
 
 conf:
   nova:
-    default:
-      oslo:
-        log:
-          debug: false
     libvirt:
-      nova:
-        conf:
       images_type: null
       images_rbd_pool: null
       images_rbd_ceph_conf: null
@@ -32,6 +26,4 @@ conf:
       disk_cachemodes: null
       hw_disk_discard: null
     upgrade_levels:
-      nova:
-        conf:
       compute: null