Fix bad Debug.Assert statements in UTF-8 processing (dotnet/coreclr#23627)
Fix bad Debug.Assert statements in UTF-8 processing (dotnet/coreclr#23627)

Signed-off-by: dotnet-bot <03c4cb6107ae99956a7681f2c97ff7104809a2bd@microsoft.com>

shimingsg/corefx,wtgodbe/corefx,wtgodbe/corefx,shimingsg/corefx,ViktorHofer/corefx,ViktorHofer/corefx,ericstj/corefx,ericstj/corefx,shimingsg/corefx,ericstj/corefx,ericstj/corefx,ViktorHofer/corefx,BrennanConroy/corefx,BrennanConroy/corefx,wtgodbe/corefx,wtgodbe/corefx,ViktorHofer/corefx,shimingsg/corefx,wtgodbe/corefx,ericstj/corefx,ericstj/corefx,wtgodbe/corefx,shimingsg/corefx,wtgodbe/corefx,ViktorHofer/corefx,BrennanConroy/corefx,shimingsg/corefx,shimingsg/corefx,ViktorHofer/corefx,ViktorHofer/corefx,ericstj/corefx