Switch VTK colormap lookuptable serializer (#6651)

* Switch VTK colormap lookuptable serializer

* Update VTK test

Author: philippjfr

panel/pane/vtk/synchronizable_serializer.py

@@ -327,7 +327,7 @@ def initializeSerializers():
         'vtkOpenGLGlyph3DMapper', glyph3DMapperSerializer)
 
     # LookupTables/TransferFunctions
-    registerInstanceSerializer('vtkLookupTable', lookupTableSerializer)
+    registerInstanceSerializer('vtkLookupTable', lookupTableSerializer2)
     registerInstanceSerializer(
         'vtkPVDiscretizableColorTransferFunction', colorTransferFunctionSerializer)
     registerInstanceSerializer(

panel/tests/pane/test_vtk.py

@@ -176,10 +176,10 @@ def test_vtk_pane_from_renwin(document, comm):
 
     # Check array release when actor are removed from scene
     ctx = pane._contexts[model.id]
-    assert len(ctx.dataArrayCache.keys()) == 5
+    assert len(ctx.dataArrayCache.keys()) == 4
     pane.remove_all_actors()
     # Default : 20s before removing arrays
-    assert len(ctx.dataArrayCache.keys()) == 5
+    assert len(ctx.dataArrayCache.keys()) == 4
     # Force 0s for removing arrays
     ctx.checkForArraysToRelease(0)