OAK-1880 : Omit Configuration Retrieval for PreAuthContext

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1601578 13f79535-47bb-0310-9956-ffa450edef68
minor improvement: login tests

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1601580 13f79535-47bb-0310-9956-ffa450edef68