With the introduction of a shared memory record typmod registry, it is no
longer necessary to remap record typmods when sending tuples between backends
so most of tqueue.c can be removed.

Author: Thomas Munro
Reviewed-By: Andres Freund
Discussion: https://postgr.es/m/CAEepm=0ZtQ-SpsgCyzzYpsXS6e=kZWqk3g5Ygn3MDV7A8dabUA@mail.gmail.com