Update trig-art-result-parser.sh
An updated version of this script was added to master in !20078 (merged) and swept to other branches. This MR brings the version from master to 21.3:
git checkout upstream/master -- Trigger/TrigValidation/TrigValTools/bin/trig-art-result-parser.sh
The changes include adding the second command line argument for list of steps to check and adding some comments in the script