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