PETRONELL-CARNUNTUM (AP).- They lived in cells barely big enough to turn around in and usually fought until they died. This was the lot of those at a sensational scientific discovery unveiled Monday: The well-preserved ruins of a gladiator school in Austria. The Carnuntum ruins are part of a city of 50,000 people 28 miles (45 kilometers) east of Vienna that flourished about 1,700 years ago, a major military and trade outpost linking the far-flung Roman empire’s Asian boundaries to its central and northern European lands. Mapped out by radar, the ruins of the gladiator school remain underground. Yet officials say the find rivals the famous Ludus Magnus — the largest of the gladiatorial training schools in Rome — in its structure. And they say the Austrian site is even more detailed than the well-known Roman ruin, down to the