pgsql: Don't set a fast default for anything but a plain table

Don't set a fast default for anything but a plain table

The fast default code added in Release 11 omitted to check that the
table a fast default was being added to was a plain table. Thus one
could be added to a foreign table, which predicably blows up. Here we
perform that check.

In addition, on the back branches, since some of these might have
escaped into the wild, if we encounter a missing value for
an attribute of something other than a plain table we ignore it.

Fixes bug #17056

Backpatch to release 11,

Reviewed by: Andres Freund, Álvaro Herrera and Tom Lane

Branch
------
REL_11_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/306c318043a9c977a248b0fbef7ca091ff863ef1

Modified Files
--------------
src/backend/catalog/heap.c                 |  9 ++++++++-
src/backend/commands/tablecmds.c           |  7 ++++---
src/backend/utils/cache/relcache.c         | 19 ++++++++++++++++++-
src/test/regress/expected/fast_default.out | 19 +++++++++++++++++++
src/test/regress/sql/fast_default.sql      | 14 ++++++++++++++
5 files changed, 63 insertions(+), 5 deletions(-)