Update search title for dark theme modes

- Remove the title in xml and set the title in PreferenceController
- Add updateRawDataToIndex to add different search title for modes
- Add updateNonIndexableKeys when the flag is off

Bug: 416328688
Test: manual search for standard/expanded and see the search result
Flag: android.view.accessibility.force_invert_color
Change-Id: I66b5422081715c6be7fc695fe1e78cfae06d9535