HPCC-8544 Remove deprecated DATASET syntax from regression test examples

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #3884 from ghalliday/issue8544eg

HPCC-8544 Remove deprecated DATASET syntax from regression test examples

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>