bp/Auth: remove unnecessary user_expires.IsExpired() check
bp/Auth: remove unnecessary user_expires.IsExpired() check

This has been done by Session::Expire() already, called by
Request::LoadSession() via Request::DetermineSession().

CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy,CM4all/beng-proxy