Fix: Add kubernetes namespace to function instance url (#4701)

### Motivation

Currently, if the kubernetes namespace set to deploy functions in is different than the one in which brokers/workers reside, get status and stats doesn't work because the url for instances does not specify the namespace.
(cherry picked from commit 8c3445ad)

pulsar-functions/runtime/src/main/java/org/apache/pulsar/functions/runtime/KubernetesRuntime.java

@@ -250,9 +250,9 @@ public class KubernetesRuntime implements Runtime {
         if (channel == null && stub == null) {
             channel = new ManagedChannel[instanceConfig.getFunctionDetails().getParallelism()];
             stub = new InstanceControlGrpc.InstanceControlFutureStub[instanceConfig.getFunctionDetails().getParallelism()];
+            String jobName = createJobName(instanceConfig.getFunctionDetails());
             for (int i = 0; i < instanceConfig.getFunctionDetails().getParallelism(); ++i) {
-                String address = createJobName(instanceConfig.getFunctionDetails()) + "-" +
-                        i + "." + createJobName(instanceConfig.getFunctionDetails());
+                String address = getServiceUrl(jobName, jobNamespace, i);
                 channel[i] = ManagedChannelBuilder.forAddress(address, GRPC_PORT)
                         .usePlaintext(true)
                         .build();
@@ -993,6 +993,10 @@ public class KubernetesRuntime implements Runtime {
         return "pf-" + tenant + "-" + namespace + "-" + functionName;
     }
 
+    private static String getServiceUrl(String jobName, String jobNamespace, int instanceId) {
+        return String.format("%s-%d.%s.%s.svc.cluster.local", jobName, instanceId, jobName, jobNamespace);
+    }
+
     public static void doChecks(Function.FunctionDetails functionDetails) {
         final String jobName = createJobName(functionDetails);
         if (!jobName.equals(jobName.toLowerCase())) {