fix: make tiny towers look both down and up (CURA-3588)
fix: make tiny towers look both down and up (CURA-3588)

Some support area is not classified as a tiny tower to be expanded downward when
- it is only small because it is the start of a support area (has no support above)
- it is only small because it is the end of when the support rests on the model (has model below)

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