Removes the regression bug#38751.

sql/ha_partition.cc:
  post push fix for bug#38804 (back port of bug#33479)
  Removes the regression bug#38751.
  
  archive relies on a ha_archive::info call to flush data before
  the copy takes place in alter table.
  
  This ensures that all partitions gets a info call, without having
  to always forward info(HA_STATUS_AUTO) to all partitions.