Refactor use of menu -variables in mr_menu::setup_menus()
- Do not assign value back and forth between 'menu' and 'pr', but call methods directly from the object we want
- Rename 'menu' + 'pr' -> 'main_menu' + 'sub_menu'
This depends on #43996, and is similarly meant as work toward debugging #43944
Now that real reason for #43944 has been found, this patch would not be really needed for stable branches. Fix for #43944 is currently built on top of this, so dropping this (from any branch) would make it necessary to rebase it.
Refactor use of menu -variables in mr_menu::setup_menus()
- Do not assign value back and forth between 'menu' and 'pr', but call methods directly from the object we want
- Rename 'menu' + 'pr' -> 'main_menu' + 'sub_menu'
This depends on #43996, and is similarly meant as work toward debugging #43944