Add test case for when subscriber table is missing a column

Add test case for when subscriber table is missing a column

We haven't had bugs in this area, but there's some not-entirely
trivial code to detect that case, so it seems good to have test
coverage for it.

Author: Peter Smith <smithpb2250@gmail.com>
Reviewed-by: vignesh C <vignesh21@gmail.com>
Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://www.postgresql.org/message-id/CAHut%2BPtX8P0EGhsk9p%3DhQGUHrzxeCSzANXSMKOvYiLX-EjdyNw@mail.gmail.com