Add delay after consumer latch for agent segment flush

The CountDownLatch ensures the consumer callback fires, but the
SkyWalking agent still needs time to flush the consumer segment
to the mock collector via gRPC. The run.sh only waits 5 seconds
after the HTTP response before collecting data. Adding a 2-second
sleep after the latch gives the agent enough time to report.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: wu-sheng

test/plugin/scenarios/rocketmq-scenario/src/main/java/test/apache/skywalking/apm/testcase/rocketmq/controller/CaseController.java

@@ -94,6 +94,8 @@ public ConsumeConcurrentlyStatus consumeMessage(List<MessageExt> msgs, ConsumeCo
             });
             thread.start();
             latch.await(30, TimeUnit.SECONDS);
+            // Wait for the agent to flush the consumer segment to the collector
+            Thread.sleep(2000);
         } catch (Exception e) {
             log.error("testcase error", e);
         }