Disable providing keystone api_version from reclass

Related-Prod: PROD-35257
Change-Id: Iff1888d18bd66c552cafd555831a3c6d26a56571
diff --git a/keystone/client/core.yml b/keystone/client/core.yml
index c965e6f..0e0c46d 100644
--- a/keystone/client/core.yml
+++ b/keystone/client/core.yml
@@ -38,6 +38,7 @@
                   options: ${_param:openstack_service_user_options}
         admin_identity:
           admin:
+            api_version: ''
             user: admin
             password: ${_param:keystone_admin_password}
             project: admin