Update preference screen title.

- Add missing title to preference screen xml so that they will be used to
set the activity title when the fragment is launched.
- Also updated some incorrect preference screen titles.
- Overrides getTitle() in preference fragments that do not use the
preference screen xml.

Bug: 64564191
Test: blaze-bin/screenshots/android/i18nscreenshots/i18nscreenshots
Change-Id: Id72d5ddf18f0962bc484de8bbd847a2e55d6371e

res/xml/bluetooth_pairing_detail.xml

@@ -16,7 +16,7 @@
 
 <PreferenceScreen
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:title="@string/bluetooth_settings">
+    android:title="@string/bluetooth_pairing_pref_title">
 
     <Preference
         android:key="device_name"/>