HPCC-10574 Support persists in roxie

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10574 Support persists in roxie

Minor fixes from code review

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5373 from richardkchapman/roxiepersist

HPCC-10574 Support persists in roxie

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>