ci: add imports and annotations to DNS and ProtocolHandler tests (#2220)

Author: kgala2

core/src/test/java/com/google/cloud/sql/core/DnsJavaResolverTest.java

@@ -22,10 +22,13 @@
 import java.util.Collection;
 import javax.naming.NameNotFoundException;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 
+@RunWith(JUnit4.class)
 public class DnsJavaResolverTest {
 
-  private static final String VALID_DOMAIN_NAME = "invalid-san-test.csqlconnectortest.com";
+  private static final String VALID_DOMAIN_NAME = "valid-san-test.csqlconnectortest.com";
   private static final String MULTI_STRING_RECORD_DOMAIN_NAME =
       "test-multi-string-txt-record.csqlconnectortest.com";
   private static final String VALID_DOMAIN_NAME_DATA =

core/src/test/java/com/google/cloud/sql/core/ProtocolHandlerTest.java

@@ -53,7 +53,10 @@
 import org.bouncycastle.cert.jcajce.JcaX509v3CertificateBuilder;
 import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder;
 import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 
+@RunWith(JUnit4.class)
 public class ProtocolHandlerTest {
 
   public static final byte[] SERVER_DATA = "hello".getBytes(StandardCharsets.UTF_8);