Fix probe filter field mapping

All probed fields should become point fields in output
5 jobs for probe-point-fields
latest
Status Name Job ID Coverage
  External
passed cdash-buildbot

passed vtk-m-dragnipur-osx-shared-debug+32bit_ids+64bit_coords+clang+tbb

00:12:17

passed vtk-m-dragnipur-osx-static-release+64bit_coords+clang+tbb

00:01:09

passed vtk-m-osheim-windows-shared-debug+ninja-vs-2017+tbb

00:08:10

passed vtk-m-osheim-windows-static-release+ninja-vs-2017+tbb

00:33:59