Small change - to avoid an extra loop for already processed reducekey

If numbers of items to take has been reached and at the same time 

"} while (Api.TryMoveNext(session, ScheduledReductions));" is done 

then "getItemsToReduceParams.ReduceKeys.Remove(reduceKey);" will not be hit 

and the next time the GetItemsToReduce is called it will start with the same reduceKey ...