[Regional prefernce] Remove U extension in locale of app list

Bug: b/270251111
Test: Manual Test
Change-Id: I2b3facfc5f7ec40a48379c79a5f0672cfe5fa7af

src/com/android/settings/applications/appinfo/AppLocaleDetails.java

@@ -213,7 +213,7 @@ public class AppLocaleDetails extends SettingsPreferenceFragment {
         if (appLocale == null) {
             return context.getString(R.string.preference_of_system_locale_summary);
         } else {
-            return LocaleHelper.getDisplayName(appLocale, appLocale, true);
+            return LocaleHelper.getDisplayName(appLocale.stripExtensions(), appLocale, true);
         }
     }
 }