[Regional Preference] Fix subtitle overlap

- Avoid to generate a new locale with extra U extension.
 - Get correct LocaleInfo from LocaleStore.

Bug: b/267268410
Test: Maunal test passed.
Change-Id: If6ef23f508c4eb7a72900a5d4e70b2f09b858663

core/java/com/android/internal/app/LocaleStore.java

@@ -563,6 +563,18 @@ public class LocaleStore {
         String id = locale.toLanguageTag();
         LocaleInfo result;
         if (!sLocaleCache.containsKey(id)) {
+            // Locale preferences can modify the language tag to current system languages, so we
+            // need to check the input locale without extra u extension except numbering system.
+            Locale filteredLocale = new Locale.Builder()
+                    .setLocale(locale.stripExtensions())
+                    .setUnicodeLocaleKeyword("nu", locale.getUnicodeLocaleType("nu"))
+                    .build();
+            if (sLocaleCache.containsKey(filteredLocale.toLanguageTag())) {
+                result = new LocaleInfo(locale);
+                // This locale is included in supported locales, so set translated be true here.
+                result.mIsTranslated = true;
+                return result;
+            }
             result = new LocaleInfo(locale);
             sLocaleCache.put(id, result);
         } else {