pgsql: Add missing assertions for required table am callbacks.

Add missing assertions for required table am callbacks. Reported-by: Ashwin Agrawal Author: Ashwin Agrawal Reviewed-by: Amit Kapila Backpatch-through: 12, where it was introduced Discussion: https://postgr.es/m/calfoeisgdzhydrjoukabzvxfjok2fq0szvmk7dzmcy6w93i...@mail.gmail.com Branch -- REL_

pgsql: Add missing assertions for required table am callbacks.

Add missing assertions for required table am callbacks. Reported-by: Ashwin Agrawal Author: Ashwin Agrawal Reviewed-by: Amit Kapila Backpatch-through: 12, where it was introduced Discussion: https://postgr.es/m/calfoeisgdzhydrjoukabzvxfjok2fq0szvmk7dzmcy6w93i...@mail.gmail.com Branch -- mast