Get rid of SET LOGGED indexes persistence kludge

This removes ATChangeIndexesPersistence() introduced by f41872d0
which was too ugly to live for long.  Instead, the correct persistence
marking is passed all the way down to reindex_index, so that the
transient relation built to contain the index relfilenode can
get marked correctly right from the start.

Author: Fabrízio de Royes Mello
Review and editorialization by Michael Paquier
                                     and Álvaro Herrera