Don't use any default www-user

Otherwise, nipap-www will always automatically create the user test with password test.

Fix for https://github.com/SpriteLink/NIPAP/issues/572
Is it possible / is there an use-case, to use it without local auth (i.e. with ldap auth)? If yes, then it should be removed. If however nipap-www is intended to always connect using local auth, it should be kept in my opinion.