vtkParticleTracerBase: remove unused function
vtkParticleTracerBase: remove unused function

Change-Id: I144b96e26ff22e4fab32f26bbfa4c80f72ba77c8

sankhesh/VTK,ashray/VTK-EVM,ashray/VTK-EVM,mspark93/VTK,msmolens/VTK,candy7393/VTK,sumedhasingla/VTK,candy7393/VTK,keithroe/vtkoptix,demarle/VTK,SimVascular/VTK,hendradarwin/VTK,SimVascular/VTK,msmolens/VTK,sankhesh/VTK,ashray/VTK-EVM,jmerkow/VTK,sumedhasingla/VTK,msmolens/VTK,sumedhasingla/VTK,SimVascular/VTK,jmerkow/VTK,johnkit/vtk-dev,keithroe/vtkoptix,sumedhasingla/VTK,jmerkow/VTK,sankhesh/VTK,keithroe/vtkoptix,msmolens/VTK,sankhesh/VTK,johnkit/vtk-dev,mspark93/VTK,jmerkow/VTK,gram526/VTK,sankhesh/VTK,SimVascular/VTK,hendradarwin/VTK,sankhesh/VTK,johnkit/vtk-dev,mspark93/VTK,hendradarwin/VTK,keithroe/vtkoptix,candy7393/VTK,candy7393/VTK,hendradarwin/VTK,gram526/VTK,msmolens/VTK,sumedhasingla/VTK,sumedhasingla/VTK,demarle/VTK,ashray/VTK-EVM,demarle/VTK,gram526/VTK,sumedhasingla/VTK,SimVascular/VTK,sankhesh/VTK,gram526/VTK,SimVascular/VTK,johnkit/vtk-dev,candy7393/VTK,msmolens/VTK,mspark93/VTK,johnkit/vtk-dev,mspark93/VTK,keithroe/vtkoptix,candy7393/VTK,demarle/VTK,demarle/VTK,johnkit/vtk-dev,gram526/VTK,ashray/VTK-EVM,hendradarwin/VTK,SimVascular/VTK,hendradarwin/VTK,mspark93/VTK,keithroe/vtkoptix,jmerkow/VTK,jmerkow/VTK,jmerkow/VTK,msmolens/VTK,sumedhasingla/VTK,gram526/VTK,demarle/VTK,ashray/VTK-EVM,mspark93/VTK,mspark93/VTK,gram526/VTK,demarle/VTK,jmerkow/VTK,sankhesh/VTK,SimVascular/VTK,gram526/VTK,msmolens/VTK,demarle/VTK,hendradarwin/VTK,keithroe/vtkoptix,keithroe/vtkoptix,ashray/VTK-EVM,johnkit/vtk-dev,candy7393/VTK,candy7393/VTK,ashray/VTK-EVM