LOCALE_SGROUPING's string and the `Grouping` field in NUMBERFMTW are confusingly different. The former, which is what is fixed here, treats a '0' as a repeat of the previous grouping. But a 0 at the end of the `Grouping` field prevents it from repeating (it repeats by default otherwise) so it's the opposite. Note that without a '0' in the LOCALE_SGROUPING string, it shouldn't even repeat in the first place.
This fixes the typical "3;0" default grouping, for example.
See: https://learn.microsoft.com/en-us/windows/win32/intl/locale-sgrouping
-- v6: kernelbase: Fix grouping repeat for number formatting.