COMP: Remove obsolete integration of VTK_USE_FILE

This commit fixes the following warning:

  CMake Deprecation Warning at /path/to/Slicer-Release/VTK-build/lib/cmake/vtk-9.1/vtk-use-file-deprecated.cmake:1 (message):
    The `VTK_USE_FILE` is no longer used starting with 8.90.
  Call Stack (most recent call first):
    UKFTractography.cmake:34 (include)
    CMakeLists.txt:97 (include)

UKFTractography.cmake

@@ -30,9 +30,6 @@ find_package(VTK COMPONENTS
   IOXML
   REQUIRED
   )
-if(VTK_USE_FILE)
-  include(${VTK_USE_FILE})
-endif()
 
 #-----------------------------------------------------------------------------
 if(DEFINED Eigen_INCLUDE_DIR)