restore-disk-image: remove duplicated uninhibit

Removes the uninhibit code from play_complete_sound, as the application calls uninhibit in a separate method directly after. The uninhibit call is still duplicated, as the both the error and the success functions call dialog_data_uninhibit and dialog_data_complete_and_unref, which then calls dialog_data_uninhibit again. I wasn't sure which one to remove, so I left them for now.