Add an additional flag guard for Private Space implementation

This a layer of flag guarding only for the implementation of Private Space features excluding the APIs. The MVP flag allow_private_profile still guards all the features including the APIs.

Bug: 326060689
Test: Manual - a few verifications that some feeatures are unavailable when this flag is disabled
Test: Run presubmits and verify that nothing breaks
Change-Id: I05f7e2f20c6132b33484bb133ce03a933ece485f

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

@@ -38,7 +38,10 @@ public class HidePrivateSpaceController extends TogglePreferenceController {
     @Override
     @AvailabilityStatus
     public int getAvailabilityStatus() {
-        return android.os.Flags.allowPrivateProfile() ? AVAILABLE : UNSUPPORTED_ON_DEVICE;
+        return android.os.Flags.allowPrivateProfile()
+                && android.multiuser.Flags.enablePrivateSpaceFeatures()
+                ? AVAILABLE
+                : UNSUPPORTED_ON_DEVICE;
     }
 
     @Override