Remove check for outermost extruder
Remove check for outermost extruder

It could never be true because we already check that extruder_nr is -1, so static_cast<unsigned int>(extruder_nr) will be an underflow to maximum unsigned int. And let's hope that you don't have 4 billion extruders.

Contributes to issue CURA-4410.

Ultimaker/CuraEngine,Ultimaker/CuraEngine