Update menu_test.py

Given that the buttons do not overlap each other, I changed the hit tests to a series of `elif` statements to show that they are mutually exclusive.  I removed the `else: pass` code which is useless and confusing.

Removed the unused function `check()` and unused variables like center, x, y, etc. I put ' ' around the parameters in `main_scene.switch_scene()` so the script would run until you actually call that method.