Misc fixes for settings

- Set device credential's Window flag to be SECURE. This prevents
  showing any pattern/pin in recent list.
- Disable tap sound on entity header

Fixes: 64339515
Fixes: 64413598
Test: visual
Test: runtest --path \
      tests/app/src/com/android/settings/password/ChooseLockGenericTest.java

src/com/android/settings/widget/EntityHeaderController.java

@@ -215,6 +215,7 @@ public class EntityHeaderController {
         final LayoutPreference pref = new LayoutPreference(uiContext, done(activity));
         // Makes sure it's the first preference onscreen.
         pref.setOrder(-1000);
+        pref.setSelectable(false);
         pref.setKey(PREF_KEY_APP_HEADER);
         return pref;
     }