Add missing ALTER TABLE statement in alltypesaggmultifiles table.

The DDL statements for adding the partitions of alltypesaggmultifiles
did not include an ALTER TABLE stmt for one of the partitions, thereby
causing the planner tests to fail when test data were loaded from a
snapshot.

Change-Id: Id4b078cd334d816d6eb8eb15e5856189701a4bca
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3305
Reviewed-by: Dimitris Tsirogiannis <dtsirogiannis@cloudera.com>
Reviewed-by: Lenni Kuff <lskuff@cloudera.com>
Tested-by: jenkins