Enable nova update_cells by default

PROD-36548

Change-Id: Ic1e431f639fa44b120b17f4f894f15cf5e377b7a
diff --git a/nova/control/single.yml b/nova/control/single.yml
index 10f9a1c..808b740 100644
--- a/nova/control/single.yml
+++ b/nova/control/single.yml
@@ -52,3 +52,4 @@
           enabled: ${_param:nova_memcache_security_enabled}
           strategy: ${_param:openstack_memcache_security_strategy}
           secret_key: ${_param:nova_memcache_secret_key}
+      update_cells: ${_param:nova_control_update_cells}