Descriptive statistics produces duplicated output on all ranks
When running in parallel, Descriptive statistics, and perhaps other stats filters too, produces duplicated output on all ranks. This is unexpected. Such aggregation filters should only produce non-empty output on rank 0.
Let's try to see if there's some reason for it and if not fix it to do what most other filters in VTK do .. i.e. only have non-empty data on rank 0.