lineage-sdk self-removing prefs: move reap from onBindViewHolder to onAttached

*) Eliminates visibility of the pref removal. You could previously
   see vertical movement of text during initial display of replaced
   prefs.

*) In addition, when reaping, use setVisible(false) instead of
   removePreference.  Otherwise, array out of bounds index exceptions
   occur in frameworks pref support libraries (as a result of moving
   from onBindViewHolder to onAttached).

Change-Id: I1a0045552572a590f89715f8d94156eddaaec469