COMP: Update legacy boolean ivar set method call to current API
COMP: Update legacy boolean ivar set method call to current API

Update legacy boolean ivar set method call to current API: the
`itk::VectorGradientMagnitudeImageFilter::m_UseImageSpacing` ivar got the
boolean macro methods in commit c6610df51b741eac1dab172f58852ad79ffdf5a2,
and the former methods were marked as legacy code.

Fixes:
```
/Users/builder/externalExamples/IO/VisibleHumanPasteWrite.cxx:72:9:
error: no member named 'SetUseImageSpacingOn' in
'itk::VectorGradientMagnitudeImageFilter<itk::Image<itk::RGBPixel<unsigned char>, 2>, float, itk::Image<float, 2> >'
  grad->SetUseImageSpacingOn();
  ~~~~  ^
1 error generated.
```

Raised for example at:
https://open.cdash.org/viewBuildError.php?buildid=6964751

BRAINSia/ITK,vfonov/ITK,BRAINSia/ITK,vfonov/ITK,Kitware/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,LucasGandel/ITK,hjmjohnson/ITK,thewtex/ITK,vfonov/ITK,LucasGandel/ITK,vfonov/ITK,thewtex/ITK,hjmjohnson/ITK,BRAINSia/ITK,Kitware/ITK,hjmjohnson/ITK,BRAINSia/ITK,thewtex/ITK,Kitware/ITK,thewtex/ITK,vfonov/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,richardbeare/ITK,LucasGandel/ITK,Kitware/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,hjmjohnson/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,Kitware/ITK,thewtex/ITK,richardbeare/ITK,BRAINSia/ITK,Kitware/ITK,hjmjohnson/ITK,thewtex/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,LucasGandel/ITK,LucasGandel/ITK,hjmjohnson/ITK,BRAINSia/ITK,richardbeare/ITK,LucasGandel/ITK,vfonov/ITK,richardbeare/ITK,vfonov/ITK