Replace autoadvance screens with waiting screen in PS setup

This change replaces the auto advancing screens shown during private
space setup flow with a single loading screen.

Recording: b/332652637#comment3

Bug: 332652637
Test: Manual
Change-Id: I470e5c6ece16cfefd0734d3daadf1d8efe963f63

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

@@ -77,7 +77,7 @@ public class PrivateSpaceMaintainer {
      *
      * <p> This method should be used by the Private Space Setup Flow ONLY.
      */
-    @VisibleForTesting
+    @VisibleForTesting(otherwise = VisibleForTesting.PACKAGE_PRIVATE)
     public final synchronized boolean createPrivateSpace() {
         if (!Flags.allowPrivateProfile()
                 || !android.multiuser.Flags.enablePrivateSpaceFeatures()) {