Enable message tracing in default mode (#388)

diff --git a/src/main/cpp/client/include/ClientConfig.h b/src/main/cpp/client/include/ClientConfig.h
index 669b220..97a1ec2 100644
--- a/src/main/cpp/client/include/ClientConfig.h
+++ b/src/main/cpp/client/include/ClientConfig.h

@@ -45,6 +45,8 @@
   virtual const std::string& getGroupName() const = 0;
 
   virtual std::string clientId() const = 0;
+
+  virtual bool isTracingEnabled() const = 0;
 };
 
 ROCKETMQ_NAMESPACE_END
\ No newline at end of file

diff --git a/src/main/cpp/client/include/ClientConfigImpl.h b/src/main/cpp/client/include/ClientConfigImpl.h
index d277190..116eb7e 100644
--- a/src/main/cpp/client/include/ClientConfigImpl.h
+++ b/src/main/cpp/client/include/ClientConfigImpl.h

@@ -70,9 +70,10 @@
     long_polling_timeout_ = timeout;
   }
 
-  bool isTracingEnabled() {
+  bool isTracingEnabled() const override {
     return enable_tracing_.load();
   }
+
   void enableTracing(bool enabled) {
     enable_tracing_.store(enabled);
   }
@@ -137,7 +138,7 @@
 
   absl::Duration long_polling_timeout_;
 
-  std::atomic<bool> enable_tracing_{false};
+  std::atomic<bool> enable_tracing_{true};
 
   static std::string steadyName();
 };

diff --git a/src/main/cpp/client/mocks/include/ClientConfigMock.h b/src/main/cpp/client/mocks/include/ClientConfigMock.h
index 703e348..115e0bf 100644
--- a/src/main/cpp/client/mocks/include/ClientConfigMock.h
+++ b/src/main/cpp/client/mocks/include/ClientConfigMock.h

@@ -33,6 +33,7 @@
   MOCK_METHOD(absl::Duration, getLongPollingTimeout, (), (const override));
   MOCK_METHOD(const std::string&, getGroupName, (), (const override));
   MOCK_METHOD(std::string, clientId, (), (const override));
+  MOCK_METHOD(bool, isTracingEnabled, (), (const override));
 };
 
 ROCKETMQ_NAMESPACE_END
\ No newline at end of file

diff --git a/src/main/cpp/tracing/exporters/include/OtlpExporter.h b/src/main/cpp/tracing/exporters/include/OtlpExporter.h
index 3b6755b..f947a38 100644
--- a/src/main/cpp/tracing/exporters/include/OtlpExporter.h
+++ b/src/main/cpp/tracing/exporters/include/OtlpExporter.h

@@ -56,6 +56,9 @@
 public:
   OtlpExporter(std::weak_ptr<ClientManager> client_manager, ClientConfig* client_config)
       : client_manager_(std::move(client_manager)), client_config_(client_config) {
+    if (client_config_->isTracingEnabled()) {
+      mode_ = TraceMode::Grpc;
+    }
   }
 
   void updateHosts(std::vector<std::string> hosts) LOCKS_EXCLUDED(hosts_mtx_) {