{heap,minimal}_expand_tuple() are unused

Hi,

As of

commit 20d3fe9009d
Author: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Date: 2020-10-26 11:36:53 -0400

In INSERT/UPDATE, use the table's real tuple descriptor as target.

heap_expand_tuple() is unused. The use before that commit was short-lived
(ba9f18abd). Before that it was unused, since

commit 171e0418b03
Author: Andres Freund <andres(at)anarazel(dot)de>
Date: 2019-02-06 01:09:32 -0800

Fix heap_getattr() handling of fast defaults.

As of

commit 4da597edf1b
Author: Andres Freund <andres(at)anarazel(dot)de>
Date: 2018-11-16 16:35:11 -0800

Make TupleTableSlots extensible, finish split of existing slot type.

minimal_expand_tuple() is unused.

Both heap_expand_tuple() and minimal_expand_tuple() being unused, make
expand_tuple() unused in turn.

I think we probably ought to remove all three in 20? I didn't find external
callers. It's nontrivial enough code that I don't think we should keep it
around just because somebody might be using it.

Thoughts?

Greetings,

Andres Freund