LOS ANGELES -- Horse racing has long withstood the deaths of its skittish, injury-prone thoroughbreds. Hollywood proved it lacks the stomach for it.HBO abruptly cancelled its racetrack drama series "Luck" this past week after three horses used in the production were injured and euthanized during 10 months of filming in the last two years.The abrupt fall of "Luck," which will end its single-season run on March 25, reveals the chasm between ...