[Thread] fix the test util of setNat64EnabledAndWait to apply old config

Bug: 356770473
Change-Id: I6d1e3d6acc9a101b3e783ab4493ed25a3aa732a1
diff --git a/thread/tests/integration/src/android/net/thread/utils/ThreadNetworkControllerWrapper.java b/thread/tests/integration/src/android/net/thread/utils/ThreadNetworkControllerWrapper.java
index 295acb8..4354702 100644
--- a/thread/tests/integration/src/android/net/thread/utils/ThreadNetworkControllerWrapper.java
+++ b/thread/tests/integration/src/android/net/thread/utils/ThreadNetworkControllerWrapper.java
@@ -220,7 +220,7 @@
     public void setNat64EnabledAndWait(boolean enabled) throws Exception {
         final ThreadConfiguration config = getConfiguration();
         final ThreadConfiguration newConfig =
-                new ThreadConfiguration.Builder().setNat64Enabled(enabled).build();
+                new ThreadConfiguration.Builder(config).setNat64Enabled(enabled).build();
         setConfigurationAndWait(newConfig);
     }