!13286 remove mutex

From: @anancds
Reviewed-by: @wilfchen,@cristoval
Signed-off-by: @cristoval

mindspore/ccsrc/ps/core/server_node.cc

@@ -150,7 +150,6 @@ bool ServerNode::Stop() {
 }
 
 bool ServerNode::Finish(const uint32_t &timeout) {
-  std::lock_guard<std::mutex> lock(finish_mutex_);
   if (is_already_finished_) {
     MS_LOG(INFO) << "Server node already finish!";
     return true;

mindspore/ccsrc/ps/core/worker_node.cc

@@ -81,7 +81,6 @@ bool WorkerNode::Stop() {
 }
 
 bool WorkerNode::Finish(const uint32_t &timeout) {
-  std::lock_guard<std::mutex> lock(finish_mutex_);
   if (is_already_finished_) {
     MS_LOG(INFO) << "Worker node already finish!";
     return true;