Reinsert comments about possible race conditions when sending bulk inventory updates on non-flag clothing editing
Fix issue in recent 3f0fa9f7 where the code start adding unknown user cache entries with no name
Comment out warning about no grid user found in UMM.TryGetUserNamesFromServices() for now
Reinstate insertion of "Unknown UserUMMAU4" now, as naive removing may be generating too many repeating user requests from other sources.

Leaves in the dropping of the client GUN8 (now 9) uuid binding message, since this was the much more common case from the viewer-side and this can only affect viewers.