BUG #14291: Fix segfault when RemoveGhostCells was off.
vtkExtractCTHPart incorrectly left the GhostCells array on the output data (under a different name) when RemoveGhostCells was off. That resulted in an array being present on certain ranks and not on other. This ended up causing segfault in the data redistribution code in ParaView since it expects ranks to have same arrays. Making vtkExtractCTHPart remove the GhostCells array when RemoveGhostCells is set to true, so that GhostCells won't be removed from the output, but the array that flags the ghost cells is.