[ISSUE #10562] Optimize PopConsumerServiceTest#transferToFsStoreTest to avoid unnecessary background threads (#10563)

- Replace consumerService.start() with consumerService.getPopConsumerStore().start()
- Replace consumerService.shutdown() with consumerService.getPopConsumerStore().shutdown()
- Avoid starting revive/cache background threads that are not needed for transferToFsStore verification
- Reduces test execution time from ~60s to ~1.3s

Author: f1amingo

broker/src/test/java/org/apache/rocketmq/broker/pop/PopConsumerServiceTest.java

@@ -464,10 +464,10 @@ public void transferToFsStoreTest() {
             .thenReturn(CompletableFuture.completedFuture(
                 new PutMessageResult(PutMessageStatus.PUT_OK, new AppendMessageResult(AppendMessageStatus.PUT_OK))));
 
-        consumerService.start();
+        consumerService.getPopConsumerStore().start();
         consumerService.getPopConsumerStore().writeRecords(consumerRecordList);
         consumerService.transferToFsStore();
-        consumerService.shutdown();
+        consumerService.getPopConsumerStore().shutdown();
     }
 
     @Test