Lock Private space at the end of PS setup.

This change is to call UserManager requestQuietModeEnabled() API at the
end of PS setup to enable quitemode for private space.

Bug: 313652502
Test: atest PrivateSpaceMaintainerTest
Verify Private space is locked state after private space setup completion.

Change-Id: I1d863f6d51ffa4bb58318696603905d35c3109b6

src/com/android/settings/privatespace/SetupSuccessFragment.java

@@ -84,6 +84,8 @@ public class SetupSuccessFragment extends InstrumentedFragment {
             if (activity != null) {
                 mMetricsFeatureProvider.action(
                         getContext(), SettingsEnums.ACTION_PRIVATE_SPACE_SETUP_DONE);
+                //TODO(b/307729746): Add a test to verify PS is locked after setup completion.
+                PrivateSpaceMaintainer.getInstance(activity).lockPrivateSpace();
                 Intent allAppsIntent = new Intent(Intent.ACTION_ALL_APPS);
                 ResolveInfo resolveInfo =
                         activity.getPackageManager()