vtkGenerateGlobalIds: handle 1 block
vtkGenerateGlobalIds needed a check to handle case where there was only 1 block of non-empty data. Added that. Also updated the test.
Addresses paraview/paraview#19638 (closed).
Backport: paraview/release
vtkGenerateGlobalIds needed a check to handle case where there was only 1 block of non-empty data. Added that. Also updated the test.
Addresses paraview/paraview#19638 (closed).
Backport: paraview/release