[cherry-pick][core] Fix the GCS memory usage high issue (picks #32302) (

#32330)

This cherry-picks #32302

Why are these changes needed?
It's not because of leak. The root cause is because we allocate more requests when start. This PR fixed it by making the number of call constant.

src/ray/rpc/grpc_server.cc

@@ -40,6 +40,7 @@ GrpcServer::GrpcServer(std::string name,
       is_closed_(true),
       num_threads_(num_threads),
       keepalive_time_ms_(keepalive_time_ms) {
+  RAY_CHECK(num_threads_ > 0) << "Num of threads in gRPC must be greater than 0";
   cqs_.resize(num_threads_);
   // Enable built in health check implemented by gRPC:
   //   https://github.com/grpc/grpc/blob/master/doc/health-checking.md
@@ -148,7 +149,7 @@ void GrpcServer::Run() {
       if (entry->GetMaxActiveRPCs() != -1) {
         buffer_size = entry->GetMaxActiveRPCs();
       }
-      for (int j = 0; j < buffer_size; j++) {
+      for (int j = 0; j < std::max(1, buffer_size / num_threads_); j++) {
         entry->CreateCall();
       }
     }