Fix animation bugs in keyguard user switcher

 - Fix bug where user detail items disappeared too quickly when closing
   the user switcher.

 - Change input to clock position algorithm so that it no longer pushes
   the clock down when the keyguard user switcher is used.

 - Cleanup updateVisibilities() for readability

Bug: 181265906
Bug: 169783558
Test: Open and close keyguard user switcher

Change-Id: Ib83a5666ca548d78e39ac2a6d0ded6925bcadcb2