Postpone containersChanged signals when doign setActive* calls
Postpone containersChanged signals when doign setActive* calls

This makes sure we do not trigger everything three times when switching
variants.

hmflash/Cura,Curahelper/Cura,Curahelper/Cura,fieldOfView/Cura,ynotstartups/Wanhao,hmflash/Cura,ynotstartups/Wanhao,fieldOfView/Cura