HPCC-10801 Don't generate through spills for roxie or thor

Note they are generally never created for thor anyway if the option to
project spill files is enabled.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5360 from ghalliday/issue10801

HPCC-10801 Don't generate through spills for roxie or thor

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>