du overstates reclaimable space for APFS clone folders

du counts APFS clones at full apparent size, so summed folder sizes can far exceed what deletion frees. Chrome code_sign_clone copies matching the installed Chrome version share blocks with it and free little, while copies of older versions should free closer to their full size. Give the user a reclaim range rather than promising the du total, and measure actual gain with df -h /System/Volumes/Data before and after deleting.