Give model_collision vector correct size from the start
Give model_collision vector correct size from the start

Saves some memory allocations and moving.

Contributes to issue CURA-4523.

alephobjects/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine,alephobjects/CuraEngine,Ultimaker/CuraEngine,ROBO3D/CuraEngine