Mark connectivity module tests as such

Add @ConnectivityModuleTest to tests for classes that are mainly used to
back the connectivity (tethering) module, in particular data classes.

This causes the test not to be run in NetworkStack/CaptivePortalLogin
MTS tests when the connectivity (tethering) module is not installed.
Skipping such tests is necessary in that configuration as they may test
behavior that is new in the latest update, and data classes backing the
connectivity module would not be affected by
NetworkStack/CaptivePortalLogin updates anyway.

Bug: 211075897
Test: atest CtsNetTestCasesLatestSdk
Change-Id: I6163cd998fc78765b903fdb7acd21e652bc711c9

tests/common/java/android/net/IpPrefixTest.java

@@ -30,6 +30,8 @@ import static org.junit.Assert.fail;
 import androidx.test.filters.SmallTest;
 import androidx.test.runner.AndroidJUnit4;
 
+import com.android.testutils.ConnectivityModuleTest;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -38,6 +40,7 @@ import java.util.Random;
 
 @RunWith(AndroidJUnit4.class)
 @SmallTest
+@ConnectivityModuleTest
 public class IpPrefixTest {
 
     private static InetAddress address(String addr) {