Use Authenticated User Id in Log4NetAppender only in Debug mode or not at all

[Dmitry-Matveev]

We should remove automated Authenticated User ID collection from Log4NetAppender code here.

Having Authenticated User ID collected by default may present a privacy concern. However, it is acceptable to collect this for debug sessions to easily differentiate debug sessions between several users reporting to the same IKey. Acceptable does not mean necessary, so simple removal of User ID collection will do as well.