Set default keystone_tokens_allow_expired_window

Set keystone_tokens_allow_expired_window = 172800

Change-Id: I65595c09ed31c302d4cdec52e73bc52abc58d80d
Related-Prod: PROD-27591
diff --git a/defaults/openstack/init.yml b/defaults/openstack/init.yml
index b0a4c7e..89cd7b2 100644
--- a/defaults/openstack/init.yml
+++ b/defaults/openstack/init.yml
@@ -114,7 +114,7 @@
     # calculated according to the definition above.
     keystone_tokens_expiration: 3600
     keystone_tokens_max_active_keys: 51
-    keystone_tokens_allow_expired_window: ''
+    keystone_tokens_allow_expired_window: 172800
     keystone_fernet_rotate_rsync_minute: 0
     keystone_fernet_rotate_rsync_hour: '*'
     # Manila