Distortion measure appears to be broken for triangle and tetrahedral cells

[user27182]

Originally posted here https://gitlab.kitware.com/vtk/vtk/-/issues/19646 but it was suggested to raise the issue here instead.

[spyridon97]

@clintonstimpson did you have times to look at it?

[clintonstimpson]

The distortion metric isn't supported as well as some other metrics, unfortunately. For linear tris and linear tets, the returned value for distortion is 1.0. This metric has been used primarily for quadratic elements.

[spyridon97]

Shall we remove it from VTK then?

[clintonstimpson]

Can you leave it in and support it for quadratic elements only?

[spyridon97]

I can do that.