AMS-HT global tray ID was calculated as ams_id * 4 (= 512 for unit 128)
but AMS-HT uses the raw ams_id directly since it has a single tray.
The backend misidentified 512 as an external spool, producing wrong
ams_mapping2. Fixed in 4 locations: frontend getGlobalTrayId(), backend
start_print() ams_mapping2 builder, print scheduler, and Spoolman tracking.