Merge topic 'backport_fixes' into paraview/release

10e7b410 Fix two warnings in unit test
bb5daad5 Add a unit test for vtkAMRFlashReader
3067c02f Mind one definition rule
b02311b4 Set max-level in Flash AMR reader
7c553c8f Remove not implemented method
e09eab0c vtkDecimatePro: Remove unused variable
00099962 TestDecimateProDegenerateTriangles: Use vtkNew instead of vtkSmartPointer
2ecb65b7 vtkDecimatePro: Change warning to include degenerate vertex ID
...

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Reviewed-by: Mathieu Westphal (Kitware) <mathieu.westphal@kitware.com>
Reviewed-by: Nicolas Vuaille <nicolas.vuaille@kitware.com>
Merge-request: !10963