Do away with a few backwards compatibility macros

Hi,

After a recent commit 6a72c42f (a related discussion [1]) which
removed MemoryContextResetAndDeleteChildren(), I think there are a
couple of other backward compatibility macros out there that can be
removed. These macros are tuplestore_donestoring() which was
introduced by commit dd04e95 21 years ago and SPI_push() and friends
which were made no-ops macros by commit 1833f1a 7 years ago. Debian
code search shows very minimal usages of these macros. Here's a patch
attached to remove them.

Thoughts?

[1] https://www.postgresql.org/message-id/20231114175953.GD2062604%40nathanxps13

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com