Update the way OMS records details about overlays

Use newly added getter methods instead of relying on internal state.

Bug: 69383160
Test: builds and unit test passes
Change-Id: Ic09ae1086c7afa039b5df11e4c8c968125784586

src/com/android/settings/display/ThemePreferenceController.java

@@ -125,7 +125,7 @@ public class ThemePreferenceController extends AbstractPreferenceController impl
     private boolean isChangeableOverlay(String packageName) {
         try {
             PackageInfo pi = mPackageManager.getPackageInfo(packageName, 0);
-            return pi != null && !pi.isStaticOverlay;
+            return pi != null && !pi.isStaticOverlayPackage();
         } catch (PackageManager.NameNotFoundException e) {
             return false;
         }