LPS-48789

Spoke with Shuyang about the possible strategies. We have a problem where the transactions commit around the same time, but each one is fetching data before either one commits. Transaction isolation levels will interfere with any solution we put together, as will the way databases handle locks. Since we can't force an ordering, the solution appears to be to make the indices non-unique while leaving the fetchBy* to return a single element. Since Liferay supports this in service.xml, this looked like the best change.