HPCC-11814 File writes failing in roxie

All attempts to write files in Roxie failing with "Cannot write file" error.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #6155 from richardkchapman/roxie-write-fail

HPCC-11814 File writes failing in roxie

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>