Add prefix pg_catalog to pg_get_statisticsobjdef_columns() in describe.c (\dX)

Hi,

I found other functions that we should add "pg_catalog" prefix in
describe.c. This fix is similar to the following commit.

=====
commit 359bcf775550aa577c86ea30a6d071487fcca1ed
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:   Sat Aug 28 12:04:15 2021 -0400

     psql \dX: reference regclass with "pg_catalog." prefix
=====

Please find attached the patch.

Regards,
Tatsuro Yamada