Remove the code to recreate hidden-to-tray state across application restarts.
It was broken after the shutdown procedures were moved to a point in time after after the main window is hidden to cover quit-by-DCOP, and Konversation 1.1 features an explicit hidden startup option that fulfills user demands more accurately anyhow.

This fixes a bug that made Konversation always hide to tray on startup regardless of the aforementioned option when the system tray icon was enabled.