Use CultureInfo.Name instead of ISOLanguageName for character matching (#16053)

src/Skia/Avalonia.Skia/FontManagerImpl.cs

@@ -55,9 +55,8 @@ namespace Avalonia.Skia
 
             culture ??= CultureInfo.CurrentUICulture;
 
-            t_languageTagBuffer ??= new string[2];
-            t_languageTagBuffer[0] = culture.TwoLetterISOLanguageName;
-            t_languageTagBuffer[1] = culture.ThreeLetterISOLanguageName;
+            t_languageTagBuffer ??= new string[1];
+            t_languageTagBuffer[0] = culture.Name;
 
             using var skTypeface = _skFontManager.MatchCharacter(null, skFontStyle, t_languageTagBuffer, codepoint);