Fix MultiBlock inspector with c/s local rendering

Fix a bug where the Multiblock Inspector hid all MultiBlock data blocks in the view when unselecting only one block.
Placeholder data type in the vtkGeometryRepresentation wasn't set to vtkMultiBlock and led to this bug in c/s local rendering.

Steps to reproduce

• Launch ParaView, remote server (can be one process)
• From developer testing data, load CompositeGlyphTree.pvm
• Open MultiBlock Inspector. Uncheck the block with path vtkMultiBlockDataSet/Block0/Block0. It will hide both blocks under vtkMultiBlockDataSet/Block1, which is incorrect.
• In fact, uncheck any individual block. Both blocks under vtkMultiBlockDataSet/Block1 will always be hidden.

Fix details

Call this->SetDefaultValues(prop, false); instead of this->SetDefaultValues(prop, true);
--> SetDefaultValues will call placeHolderProp->SetElement(0, this->InputDataType); instead of placeHolderProp->SetElement(0, this->InputDataType);
--> InputDataType will be pushed on server
--> The Placeholder in vtkGeometryRepresentation will have the good data type
--> Prevent bug when selecting through the hierarchy the in MB inspector

Left: right image, right: wrong image

Backport: release