fix: ensure super.stop() is called exactly once in CanalRabbitMQProducer (#5578)

Previously super.stop() was called both inside the try block and after
the catch blocks. On success it was invoked twice; on IOException it was
never reached. Move super.stop() to a finally block so it executes
exactly once regardless of whether close() succeeds or fails.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

connector/rabbitmq-connector/src/main/java/com/alibaba/otter/canal/connector/rabbitmq/producer/CanalRabbitMQProducer.java

@@ -210,13 +210,12 @@ public class CanalRabbitMQProducer extends AbstractMQProducer implements CanalMQ
         try {
             this.channel.close();
             this.connect.close();
-            super.stop();
         } catch (AlreadyClosedException ex) {
             logger.error("Connection is already closed", ex);
         } catch (IOException | TimeoutException ex) {
             throw new CanalException("Stop RabbitMQ producer error", ex);
+        } finally {
+            super.stop();
         }
-
-        super.stop();
     }
 }