Replace twophase_XLogPageRead() with read_local_xlog_page() for generic xlog page read for two phase code.
Replace twophase_XLogPageRead() with read_local_xlog_page() for generic xlog page read for two phase code.

logical_read_local_xlog_page() was renamed as read_local_xlog_page() in
postgres commit 422a55a68784fd00f4514834f3649140a9166fa5 for generic xlog page
read. We should use that for two phase state xlog reading given that comes from
upstream and also it seems that twophase_XLogPageRead() is buggy also (e.g.  it
does not consider cross segment file). We backport
422a55a68784fd00f4514834f3649140a9166fa5 also because it is used by another
patch that we will backport also (see below 2).

This patch removes two FIXMEs also:

1. Previously XLogCloseReadRecord() was needed to re-initialize for
   XLogPageRead() (typically after startup ends), but now we of course
   do not need that, so removing the comment below.

    * GPDB_93_MERGE_FIXME: GPDB used to do XLogCloseReadRecord() and then read,
    * do we need to perform something similar with new interface.

2.  The FIXME below is deleted when we replace the
    function twophase_XLogPageRead(), but the comment is reasonable
    because it is possible that PREPARE xlog exists in an older segment
    file with previous timeline id even during mirror promotion some
    previous xlogs are copied when creating the new segment file for
    the new timeline id. We backport postgres patch 49e4196 to address this.

   // GPDB_93_MERGE_FIXME: Is ThisTimeLineID correct here? Do we need to
   // fetch prepare records for past timelines, after promotion?

ashwinstar/gpdb,xinzweb/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,adam8157/gpdb,50wu/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,xinzweb/gpdb,adam8157/gpdb,lisakowen/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,lisakowen/gpdb,greenplum-db/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,lisakowen/gpdb,greenplum-db/gpdb,adam8157/gpdb,ashwinstar/gpdb,50wu/gpdb,50wu/gpdb,lisakowen/gpdb,jmcatamney/gpdb,adam8157/gpdb,greenplum-db/gpdb,adam8157/gpdb,adam8157/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,50wu/gpdb,jmcatamney/gpdb,lisakowen/gpdb,xinzweb/gpdb,jmcatamney/gpdb,50wu/gpdb,xinzweb/gpdb,xinzweb/gpdb,jmcatamney/gpdb,adam8157/gpdb,jmcatamney/gpdb,lisakowen/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,xinzweb/gpdb,lisakowen/gpdb,50wu/gpdb,50wu/gpdb