HPCC-8727 ONCE dictionaries should not be serialized to the slaves

Additional fixes required, revealed by regression suite after recent codegen
fix in this area.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #3974 from richardkchapman/remoteonce

HPCC-8727 ONCE dictionaries should not be serialized to the slaves

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>