fix wrong context bug in cxx_api

mindspore/ccsrc/cxx_api/graph/ascend/ascend_graph_impl.cc

@@ -304,6 +304,7 @@ AscendGraphImpl::MsEnvGuard::MsEnvGuard(uint32_t device_id) {
   ms_context->set_param<int>(MS_CTX_EXECUTION_MODE, kGraphMode);
   ms_context->set_param<uint32_t>(MS_CTX_DEVICE_ID, device_id_);
   ms_context->set_param<std::string>(MS_CTX_DEVICE_TARGET, kAscendDevice);
+  ms_context->set_param<bool>(MS_CTX_IS_MULTI_GRAPH_SINK, true);
 
   if (ms_context->get_param<bool>(MS_CTX_ENABLE_HCCL)) {
     pipeline::InitHccl();