Ignore some ConnectivityManagerTest CTS tests that can't be run in the instant app mode

1. testIsPrivateDnsBroken: It requires the
   permission:android.permission.WRITE_SECURE_SETTINGS. But the
   WRITE_SECURE_SETTINGS permission can't be granted to instant
   apps.
2. testSetOemNetworkPreferenceForTestOnlyPref: Instant apps can't
   create test networks.
3. testSetOemNetworkPreferenceForTestPref: Instant apps can't
   create test networks.

Bug: 191678254
Bug: 191680108
Test: atest android.net.cts.ConnectivityManagerTest --instant
      atest CtsNetTestCasesLatestSdk:ConnectivityManagerTest --instant
Original-Change: https://android-review.googlesource.com/1743373
Merged-In: Ice43bcf7a1dc34f4a54fefba7f408767f0a4341e
Change-Id: Ice43bcf7a1dc34f4a54fefba7f408767f0a4341e
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index eb9c305..c2613c8 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -698,6 +698,7 @@
                 .build();
     }
 
+    @AppModeFull(reason = "WRITE_SECURE_SETTINGS permission can't be granted to instant apps")
     @Test @IgnoreUpTo(Build.VERSION_CODES.Q)
     public void testIsPrivateDnsBroken() throws InterruptedException {
         final String invalidPrivateDnsServer = "invalidhostname.example.com";
@@ -2202,7 +2203,7 @@
      * For specified apps, validate networks are prioritized in order: unmetered, TEST transport,
      * default network.
      */
-    @AppModeFull(reason = "Cannot get WifiManager in instant app mode")
+    @AppModeFull(reason = "Instant apps cannot create test networks")
     @Test
     public void testSetOemNetworkPreferenceForTestPref() throws Exception {
         // Cannot use @IgnoreUpTo(Build.VERSION_CODES.R) because this test also requires API 31
@@ -2262,6 +2263,7 @@
      * Verify that per-app OEM network preference functions as expected for network pref TEST_ONLY.
      * For specified apps, validate that only TEST transport type networks are used.
      */
+    @AppModeFull(reason = "Instant apps cannot create test networks")
     @Test
     public void testSetOemNetworkPreferenceForTestOnlyPref() throws Exception {
         // Cannot use @IgnoreUpTo(Build.VERSION_CODES.R) because this test also requires API 31