Since this benchmark has been significantly modified and needs to be renamed, we can also lower the workload by a factor of 10, to keep up with the best practices.
The old benchmark that uses `NSDecimalNumber` as the tested class is renamed to `MapReduceNSDecimalNumber` and the renamed `MapReduceClass2` now newly measures Swift class `Box` that wrap an `Int`. Short versions were modified analogously.
MapReduceClass had setup overhead fo 868 μs (7%).
Setup overhead of MapReduceClassShort was practically lost in the measurement noise from it’s artificially high base load, but it was there.
Extracting the decimal array initialization into `SetUpFunction` also takes out the cost of releasing the [NSDecimalNumber], which turns out to be about half of the measured runtime in the case of MapReduceClass benchmark. This significantly changes the reported runtimes (to about half), therfore the modified benchmarks get a new name with suffix `2`.
