Don't use Wuffs (#7785)

This code path isn't stable yet.

Fixes flutter/flutter#27718
Reopens flutter/flutter#23838

tools/gn

@@ -85,7 +85,6 @@ def to_gn_args(args):
     gn_args['skia_use_x11'] = False        # Never add the X11 dependency (only takes effect on Linux).
     gn_args['skia_use_expat'] = args.target_os == 'android'
     gn_args['skia_use_fontconfig'] = False # Use the custom font manager instead.
-    gn_args['skia_use_wuffs'] = not sys.platform.startswith(('cygwin', 'win'))
     gn_args['is_official_build'] = True    # Disable Skia test utilities.
 
     gn_args['is_debug'] = args.unoptimized