COMP: Remove unused variable

Remove unused variable.

Fixes:
```
Modules/Remote/LabelErodeDilate/include/itkLabelSetUtils.h:260:37:
 warning: unused variable 'initPixelValue' [-Wunused-variable]

  260 |   const typename TInIter::PixelType initPixelValue = 0.0;
      |                                     ^~~~~~~~~~~~~~
```

raised for example in:
https://open.cdash.org/viewBuildError.php?type=1&buildid=10316578

Introducing the variable was an oversight in commit 108b0ba.

Author: jhlegarreta

include/itkLabelSetUtils.h

@@ -257,7 +257,6 @@ doOneDimensionErodeFirstPass(TInIter &          inputIterator,
   //  const RealType magnitude = (magnitudeSign * iscale * iscale)/(2.0 *
   // sigma);
   const RealType                    magnitude = (magnitudeSign * iscale * iscale) / (2.0);
-  const typename TInIter::PixelType initPixelValue = 0.0;
   LineBufferType                    lineBuf(lineLength, 0.0);
   LabelBufferType                   labBuf(lineLength, 0.0);