Remove reference to machine_extruder_count
Remove reference to machine_extruder_count

This setting is not defined in this definition so it can't find the value of it here. I've re-introduced the maximum_value statically in the Jedi implementations of this setting.

Contributes to issue CURA-1278 and CURA-351.

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