Misc tweaks to Indexable usage and tests.

- Make SettingsPreferenceFragment implement Indexable directly
- Add existing fragments that are SettingsPrefFragment but not Indexable
  to grandfather list.
- Fix "font size" fragment so it shows up in search properly.
- Remove duplicates for "lock screen display", "Screen saver".

Bug: 70720645
Test: robotests
Change-Id: I44ce0cac0fdf5e882b315861bb4bebc45dbe01e6
diff --git a/src/com/android/settings/inputmethod/PhysicalKeyboardFragment.java b/src/com/android/settings/inputmethod/PhysicalKeyboardFragment.java
index 734c290..765a834 100644
--- a/src/com/android/settings/inputmethod/PhysicalKeyboardFragment.java
+++ b/src/com/android/settings/inputmethod/PhysicalKeyboardFragment.java
@@ -58,7 +58,7 @@
 @SearchIndexable
 public final class PhysicalKeyboardFragment extends SettingsPreferenceFragment
         implements InputManager.InputDeviceListener,
-        KeyboardLayoutDialogFragment.OnSetupKeyboardLayoutsListener, Indexable {
+        KeyboardLayoutDialogFragment.OnSetupKeyboardLayoutsListener {
 
     private static final String KEYBOARD_ASSISTANCE_CATEGORY = "keyboard_assistance_category";
     private static final String SHOW_VIRTUAL_KEYBOARD_SWITCH = "show_virtual_keyboard_switch";