3D Centered Tetrahedra based meshes for 1.5D simulations have issues in the interfaces

[AlejandroMunozManterola]

There seems to be an issue with the flux transmission between internal interfaces. Due to the angled nature of tetrahedra faces, the issue might be located in the normal treatment.

Strangely, this issue does not seem to appear in the Upwind version of this problem.