I met a cello teacher that asked why his student practiced in the perfect temperature and ideal environment when on state, her hands were sweaty and she usually felt cold.
He then told her, you should do your best to emulate the performance environment. If your hands sweat, on stage, make your hands sweat when you practice.
Pretty extreme!
I think you just have to tackle what your nervous tick is and just learn to perform under those circumstances.
I used to have a friend whose hands trembled and sweat LIKE CRAZY, and she was just got used to it over the years. Went on stage after her performance, and the piano was so slippery. Now, I bring a cloth on stage just in case.