do away with ALTER TABLE "Recurse" subcmd types

I already mentioned this in [1]: we can remove a few subcmd types that
were added to support exec-time recursion, by keeping a separate flag
for it. We're already doing that for alter trigger operations, so this
patch just extends that to the other subcommand types that need it.

There's no visible change, just some code simplification.

[1] https://postgr.es/m/20220729184452.2i4xcru3lzey76m6@alvherre.pgsql

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"All rings of power are equal,
But some rings of power are more equal than others."
(George Orwell's The Lord of the Rings)