message: Always create a Rendezvous in RemoteCallOp.
  This change does not affect existing functionality, and enables RemoteCallOp to work in environments where a Rendezvous is not necessarily available (e.g. in a function called from an IteratorContext).
diff: @@ -318,7 +318,7 @@ class RemoteCallOp : public AsyncOpKernel {
  if (opts.source_device != target_device) {
  opts.remote_execution = true;
  }
  - opts.rendezvous = ctx->rendezvous();
  + opts.create_rendezvous = true;
  std::vector<Tensor> args;
  args.reserve(arguments.size());
  for (const Tensor& argument : arguments) {
  