[pulsar-storm] Fix: Authentication is failing with storm adapter (#6782)

### Motivation
In #4284, made [Authentication](https://github.com/apache/pulsar/blob/master/pulsar-client-api/src/main/java/org/apache/pulsar/client/api/Authentication.java#L33) a transient under ClientConfigurationData. `Authentication` is a serializable class because ClientConfig is used in Storm and Spark adapter to pass client configuration and Storm serializes and deserializes spout and bolt while executing them in topology. Now, after making `Authentication` transient variable storm always deserializes it as null and authentication fails. Also `Authentication` is a serializable class so, any auth-implementation must be serializable.

### Modification
Keep Authentication param serializable.

### Result
It fixes pulsar-storm with authentication enabled.
diff --git a/pulsar-flink/src/test/java/org/apache/flink/streaming/connectors/pulsar/CachedPulsarClientTest.java b/pulsar-flink/src/test/java/org/apache/flink/streaming/connectors/pulsar/CachedPulsarClientTest.java
index 39cdca1..0c81c4a 100644
--- a/pulsar-flink/src/test/java/org/apache/flink/streaming/connectors/pulsar/CachedPulsarClientTest.java
+++ b/pulsar-flink/src/test/java/org/apache/flink/streaming/connectors/pulsar/CachedPulsarClientTest.java
@@ -27,7 +27,7 @@
 import org.apache.pulsar.client.impl.conf.ClientConfigurationData;
 import org.mockito.Mockito;
 import org.powermock.api.mockito.PowerMockito;
-import org.testng.annotations.BeforeTest;
+import org.testng.annotations.BeforeMethod;
 import org.testng.annotations.Test;
 
 /**
@@ -37,7 +37,7 @@
 
     private static final String SERVICE_URL = "pulsar://localhost:6650";
 
-    @BeforeTest
+    @BeforeMethod
     public void clearCache() {
         CachedPulsarClient.clear();
     }