Created by: grygielski

Following https://github.com/PaddlePaddle/Paddle/pull/23041#discussion_r397203631 we are deleting is_test attribute from activation operators. @luotao1 I've noticed op_list in is_test_pass.cc that basically forces some operators to have is_test attribute even if it's not specified in OpMaker. I've deleted DNNL related ones from there. I assume this was created to have models backward compatibility. Can you help me determine if it's ok?