message: [XLA:Python] Remove unnecessary Python buffer tree code in BufferFromPyval.
  BufferFromPyval hasn't supported Python buffer trees for some time.
diff: @@ -104,7 +104,6 @@ StatusOr<std::unique_ptr<PyBuffer>> PyClient::BufferFromPyval(
  return InvalidArgument("from_python argument must be an array.");
  }
  - TF_ASSIGN_OR_RETURN(PythonBufferTree tree, GetPythonBufferTree(argument));
  std::shared_ptr<PythonRefManager::ManagedPyObjects> py_buffer_ref =
  GlobalPyRefManager()->ManageReference(std::move(c->array));
  