Reduce duplication in reduce kernels if extracting common code to device function does not hurt performance

#9722 and #9740 introduced new kernels to handle device resident problem sizes. Since they share code with the existing kernels, it would make sense to extract that code to a common helper, however that resulted in SASS differences to the existing kernels.

We should measure if these sass differences have a negative impact on performance. If the impact is negligible, we should refactor the code to avoid duplication.