Fix potential catalog corruption with temporary identity columns

If a temporary table with an identity column and ON COMMIT DROP is
created in a single-statement transaction (not useful, but allowed),
it would leave the catalog corrupted.  We need to add a
CommandCounterIncrement() so that PreCommit_on_commit_actions() sees
the created dependency between table and sequence and can clean it
up.

The analogous and more useful case of doing this in a transaction
block already runs some CommandCounterIncrement() before it gets to
the on-commit cleanup, so it wasn't a problem in practical use.

Several locations for placing the new CommandCounterIncrement() call
were discussed.  This patch places it at the end of
standard_ProcessUtility().  That would also help if other commands
were to create catalog entries that some on-commit action would like
to see.

Bug: #15631
Reported-by: Serge Latyntsev <dnsl48@gmail.com>
Author: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>