vtkGeometryFilter: Fix ijk assignment for non fast-mode
vtkGeometryFilter: Fix ijk assignment for non fast-mode. The previous 5 was accidentally placed there after copying/changing the algorithm back in May/June.
This MR fixes these failures https://open.cdash.org/viewTest.php?onlyfailed&buildid=8423215.
Backport: paraview/release
Edited by Spiros Tsalikis