STYLE: Remove AdvancedImageMomentsCalculator::m_NumberOfPixelsCounted

This private member variable just wasn't used anywhere.

Author: N-Dekker

Common/Transforms/itkAdvancedImageMomentsCalculator.h

@@ -313,7 +313,6 @@ class ITK_TEMPLATE_EXPORT AdvancedImageMomentsCalculator : public Object
 
   mutable std::vector<AlignedComputePerThreadStruct> m_ComputePerThreadVariables{};
   bool                                               m_UseMultiThread{};
-  SizeValueType                                      m_NumberOfPixelsCounted{};
 
   SizeValueType               m_NumberOfSamplesForCenteredTransformInitialization{};
   InputPixelType              m_LowerThresholdForCenterGravity{};