HPCC-12302 Regression Test Engine doesn't use platform specific result
file when run setup.

Fix expected result path generation bug.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #6467 from AttilaVamos/HPCC-12302-fix

HPCC-12302 Regression Test Engine doesn't use platform specific result file when run setup.

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>