HPCC-11924 Improve result_lib display of sets

Remove schema generated column for "All" and populate item column
with "All" when specified.

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #6322 from afishbeck/resultDisplaySetALL

HPCC-11924 Improve result_lib display of sets

Reviewed-By: Kevin Wang <kevin.wang@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>