generateSupportAreasForMesh: Rename variables to remove support_
generateSupportAreasForMesh: Rename variables to remove support_

Because it's all about support, we shouldn't need to put support_ before everything.

Contributes to issue CURA-4523.

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