WifiStack: Fix build error occurred by not allowed artifact path

WifiRRROverlaySampleApp.apk has to be in system/* instead of product/*
because of mainline_system.mk

Bug: 151693586
Test: Verified that the sample overlay app can override configs.
(cherry-picked from go/pag/1604758)

Change-Id: Ia0232e4f6e976a53302d62c985a3d1c34b0f5a8a
diff --git a/RROOverlaySampleApp/Android.bp b/RROOverlaySampleApp/Android.bp
index 52c56d9..0ce841f 100644
--- a/RROOverlaySampleApp/Android.bp
+++ b/RROOverlaySampleApp/Android.bp
@@ -20,6 +20,5 @@
         "res",
     ],
     manifest: "AndroidManifest.xml",
-    sdk_version: "current",
-    product_specific: true
+    sdk_version: "current"
 }