I won't wish you good luck because you don't need luck
That's right. The last thing you need on any flying test is good luck. If you get good luck and pass by accident what's going to happen when you're on your own and get bad luck?
I think it's correct to wish people
bad luck for flying tests; if you get the bad luck with an examiner sitting next to you and cope with it well you're much better off for the future.