HPCC-11739 Roxie cluster priorities not set correctly

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #6099 from richardkchapman/roxie-cluster-priority-fix

HPCC-11739 Roxie cluster priorities not set correctly

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>