HPCC-10629 NOTIFY not supported in Roxie

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5378 from richardkchapman/roxie-notify

HPCC-10629 NOTIFY not supported in Roxie

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>