Always nullify serializer to free memory

include/grpcpp/impl/codegen/call_op_set.h

@@ -324,8 +324,8 @@ class CallOpSendMessage {
     }
     if (msg_ != nullptr) {
       GPR_CODEGEN_ASSERT(serializer_(msg_).ok());
-      serializer_ = nullptr;
     }
+    serializer_ = nullptr;
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_MESSAGE;
     op->flags = write_options_.flags();

include/grpcpp/impl/codegen/interceptor_common.h

@@ -98,9 +98,7 @@ class InterceptorBatchMethodsImpl
     *orig_send_message_ = message;
   }
 
-  bool GetSendMessageStatus() override {
+  bool GetSendMessageStatus() override { return !*fail_send_message_; }
-    return !*fail_send_message_;
-  }
 
   std::multimap<grpc::string, grpc::string>* GetSendInitialMetadata() override {
     return send_initial_metadata_;