Fixes #6367 - cnsmer_shw auth client/usr BZ1112664

access denied received when registering using subscription-manger using the
consumerId flag was for a preliminary call to check that the consumer
exists. This allows :consumer_show authorization through client or user
instead of solely by client.
What about using https://github.com/Katello/katello/blob/master/test/support/auth_support.rb#L69 to setup a user with the minimal permission set to visit this URL instead of admin?