Force idle_in_transaction_session_timeout off in pg_dump and autovacuum.

We disable statement_timeout and lock_timeout during dump and restore, to
prevent any global settings that might exist from breaking routine backups.
Commit c6dda1f4 should have added idle_in_transaction_session_timeout to
that list, but failed to.

Another place where these timeouts get turned off is autovacuum.  While
I doubt an idle timeout could fire there, it seems better to be safe than
sorry.

pg_dump issue noted by Bernd Helmle, the other one found by grepping.

Report: <352F9B77DB5D3082578D17BB@eje.land.credativ.lan>