vtkPVDataDeliveryManager was using incorrect geometry size for
vtkImageVolumeRepresentation. vtkImageVolumeRepresentation needed to
report the true data size to vtkPVDataDeliveryManager for it make the
correct decision. This commit fixes that by adding an API to
vtkPVDataDeliveryManager to pass in a "true-data-size" when passing
dataset to deliver.

Change-Id: Iff1bc45e18f35b1bf1c57739b23daa7441c5ecd8