[Panlingual] Removed the feature flag of per app language.

 - App language has already landed, so this flag can be removed.

Bug: b/209775925
Test: Maunal test passed.
Change-Id: Ie3a03ff5d86ab40b210dd26452133b81dbe595df
Merged-In: I6345bfb726234c1dd33dda02d87ca9868725c73c
diff --git a/core/java/android/util/FeatureFlagUtils.java b/core/java/android/util/FeatureFlagUtils.java
index 195cf82..9874d6a 100644
--- a/core/java/android/util/FeatureFlagUtils.java
+++ b/core/java/android/util/FeatureFlagUtils.java
@@ -52,12 +52,6 @@
     public static final String SETTINGS_SUPPORT_LARGE_SCREEN = "settings_support_large_screen";
 
     /**
-     * Support per app's language selection
-     * @hide
-     */
-    public static final String SETTINGS_APP_LANGUAGE_SELECTION = "settings_app_language_selection";
-
-    /**
      * Support locale opt-out and opt-in switch for per app's language.
      * @hide
      */
@@ -115,7 +109,6 @@
         DEFAULT_FLAGS.put(SETTINGS_ENABLE_SECURITY_HUB, "true");
         DEFAULT_FLAGS.put(SETTINGS_SUPPORT_LARGE_SCREEN, "true");
         DEFAULT_FLAGS.put("settings_search_always_expand", "true");
-        DEFAULT_FLAGS.put(SETTINGS_APP_LANGUAGE_SELECTION, "true");
         DEFAULT_FLAGS.put(SETTINGS_APP_LOCALE_OPT_IN_ENABLED, "true");
         DEFAULT_FLAGS.put(SETTINGS_ENABLE_MONITOR_PHANTOM_PROCS, "true");
         DEFAULT_FLAGS.put(SETTINGS_APP_ALLOW_DARK_THEME_ACTIVATION_AT_BEDTIME, "true");
@@ -127,7 +120,6 @@
     private static final Set<String> PERSISTENT_FLAGS;
     static {
         PERSISTENT_FLAGS = new HashSet<>();
-        PERSISTENT_FLAGS.add(SETTINGS_APP_LANGUAGE_SELECTION);
         PERSISTENT_FLAGS.add(SETTINGS_APP_LOCALE_OPT_IN_ENABLED);
         PERSISTENT_FLAGS.add(SETTINGS_SUPPORT_LARGE_SCREEN);
         PERSISTENT_FLAGS.add(SETTINGS_ENABLE_MONITOR_PHANTOM_PROCS);