Clear the prepared statements if the catalog might have changed

Clear the prepared statements if the catalog might have changed

This could happen on DROP (and re-creation) of some object or on the
implicit drop caused by a rollback.

Issues happen if a prepared transaction is executed after an object has
been dropped: see
https://github.com/sqlalchemy/sqlalchemy/issues/6842#issuecomment-925131836

Postgres devs suggestion is to avoid to do that: see
https://www.postgresql.org/message-id/2220999.1632335261%40sss.pgh.pa.us