oslo policy: check puppet resource instead of actual config in spec

Change-Id: I046d35176119b911980b457a5ec93646c9329ce0

spec/classes/keystone_policy_spec.rb

@@ -20,7 +20,9 @@ describe 'keystone::policy' do
         :key   => 'context_is_admin',
         :value => 'foo:bar'
       })
-      is_expected.to contain_keystone_config('oslo_policy/policy_file').with_value('/etc/keystone/policy.json')
+      is_expected.to contain_oslo__policy('keystone_config').with(
+        :policy_file => '/etc/keystone/policy.json',
+      )
     end
   end