Sweeping !26826 from 21.3 to 21.0. Adapt trigger validation scipts to changes in ART

Adapt trigger validation scipts to changes in ART

See merge request !26826 (merged)

Trigger/TrigValidation/TriggerTest/test/exec_athena_art_trigger_validation.sh

@@ -60,7 +60,12 @@ fi
 ######################################
 
 # Generate empty PoolFileCatalog.xml - this prevents incorrect handling of crashes on the grid
-art.py createpoolfile
+# Generate empty PoolFileCatalog.xml - this prevents incorrect handling of crashes on the grid
+ART_AVAILABLE=`which art.py >/dev/null 2>&1; echo $?`
+if [[ $ART_AVAILABLE == "0" ]]; then
+  echo "Executing art.py createpoolfile"
+  art.py createpoolfile
+fi
 
 ######################################