Set fixed-key key manager

With the key manager refactoring in nova and cinder, the key manager
class will need to be explicitly set.

Nova key manager refactoring: Ib563b0ea4b8b4bc1833bf52bf49a68546c384996
Cinder key manager refactoring: Ief8885bb4ca8d62b03cf1a52c25dd0e62c835bfe

Change-Id: I733279864ee1a4aaffc9c8eed81b5e12f8d8821b
Implements: blueprint use-castellan-key-manager
diff --git a/lib/cinder b/lib/cinder
index c4a49cd..c7ce0f5 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -283,6 +283,8 @@
 
     iniset $CINDER_CONF DEFAULT os_region_name "$REGION_NAME"
 
+    iniset $CINDER_CONF key_manager api_class cinder.keymgr.conf_key_mgr.ConfKeyManager
+
     if is_service_enabled c-vol && [[ -n "$CINDER_ENABLED_BACKENDS" ]]; then
         local enabled_backends=""
         local default_name=""