Short circuit event count when limit present

similar to #322 https://github.com/usgs/earthquake-event-ws/pull/322

The FdsnEventWebService logic is a little more complex, because it checks for deleted events, but a similar change should be feasible to remove the separate count query when a limit parameter is included.

• Also, set max on limit during request validation for product service, similar to https://github.com/usgs/earthquake-event-ws/blob/master/src/lib/classes/fdsn/FDSNEventWebService.class.php#L380

• This ticket was migrated from earthquake-event-ws in github https://github.com/usgs/earthquake-event-ws/issues/323