Fix DnsResolverTest for instant mode

add AppModeFull@ to DnsResolverTest since WRITE_SECURE_SETTINGS
could not be ganted in instant mode.

Bug: 134897744
Test: atest DnsResolverTest
      atest DnsResolverTest --instant

Change-Id: I267c19af1a1c5544ca752a364335ec728a478bb2
(cherry picked from commit 2af244f4127883ed967089f550f2cfe07936416d)
diff --git a/tests/cts/net/src/android/net/cts/DnsResolverTest.java b/tests/cts/net/src/android/net/cts/DnsResolverTest.java
index e16fce0..1ff2090 100644
--- a/tests/cts/net/src/android/net/cts/DnsResolverTest.java
+++ b/tests/cts/net/src/android/net/cts/DnsResolverTest.java
@@ -39,6 +39,7 @@
 import android.os.CancellationSignal;
 import android.os.Handler;
 import android.os.Looper;
+import android.platform.test.annotations.AppModeFull;
 import android.provider.Settings;
 import android.system.ErrnoException;
 import android.test.AndroidTestCase;
@@ -53,6 +54,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 
+@AppModeFull(reason = "WRITE_SECURE_SETTINGS permission can't be granted to instant apps")
 public class DnsResolverTest extends AndroidTestCase {
     private static final String TAG = "DnsResolverTest";
     private static final char[] HEX_CHARS = {