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

src/com/android/settings/dream/WhenToDreamPicker.java

@@ -37,6 +37,11 @@ public class WhenToDreamPicker extends RadioButtonPickerFragment {
         mBackend = DreamBackend.getInstance(context);
     }
 
+    @Override
+    protected int getPreferenceScreenResId() {
+        return R.xml.when_to_dream_settings;
+    }
+
     @Override
     public int getMetricsCategory() {
         return MetricsProto.MetricsEvent.DREAM;