Remove testing include from ZFP worklet headers
Several of the ZFP worklet headers included `vtkm/cont/testing/ MakeTestDataSet.h`. This is a problem because if testing is turned off, then `MakeTestDataSet.h` attempts to include a file that is not generated, so the compile just fails if testing is off (and the testing library is not on). This include must be a remanent of some old testing code during development. It can be safely removed.