Update VpnTest#testDefault to use otherUid that has internet permission

Bug: 342557183
Test: VpnTest
Change-Id: If4a256df9ef96285c65dd285c7d37696dbd82298
diff --git a/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java b/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
index e88c105..e186c6b 100755
--- a/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
+++ b/tests/cts/hostside/app/src/com/android/cts/net/hostside/VpnTest.java
@@ -971,8 +971,12 @@
         final TestableNetworkCallback otherUidCallback = new TestableNetworkCallback();
         final TestableNetworkCallback myUidCallback = new TestableNetworkCallback();
         if (SdkLevel.isAtLeastS()) {
-            final int otherUid =
-                    UserHandle.of(5 /* userId */).getUid(Process.FIRST_APPLICATION_UID);
+            // Using the same appId with the test to make sure otherUid has the internet permission.
+            // This works because the UID permission map only stores the app ID and not the whole
+            // UID. If the otherUid does not have the internet permission, network access from
+            // otherUid could be considered blocked on V+.
+            final int appId = UserHandle.getAppId(Process.myUid());
+            final int otherUid = UserHandle.of(5 /* userId */).getUid(appId);
             final Handler h = new Handler(Looper.getMainLooper());
             runWithShellPermissionIdentity(() -> {
                 registerSystemDefaultNetworkCallback(systemDefaultCallback, h);