It is still there, but it has been changed how it works.
If you put your factories into control group(s) (Ctrl + [Number]) then they are picked up by the idle factories check, and the F2 key works. I would prefer to not have to put them into control groups to enable the idle factory shortcut, but there are some benefits to the way it works now that I do not use.
Thanks for the clarification. I hope this is changed in a patch so that a control group is not required. I also hope that additional options (e.g. select all factories (even if not idle), select all idle armories, select all armories, etc) are added as well.
