Hide "Clone View" and pair view options from the Menubar
Based on the [discussion](https://gitlab.com/flightgear/flightgear/-/issues/3029#note_2314553644) in flightgear#3029. the "Clone View" and pair view options should be disabled on 2024.1.1, as they have a number of bugs and are not quite yet ready for prime-time.
issue