mixing_elbow.vtk is an invalid VTK dataset

### 🔍 Before submitting the issue

- [X] I have searched among the existing issues
- [X] I am using a Python virtual environment

### 🐞 Description of the bug

The mixing_elbow.vtk dataset does render in most VTK pipelines. However, VTK's cell validator (vtkCellValidator) shows fundamental problems with the grid. Almost every cell has a validity value of 52 (110100 in binary), indicating that they are invalidate due to IntersectingEdges, NoncontiguousEdges, and Nonconvex.

### 📝 Steps to reproduce

Two ways to reproduce:
1. Add a vtkCellValidator to a VTK pipeline. Look at the resulting values of the ValidityState scalar. They should be all zero. If they are not, look at the reference in [vtkCellValidator.h](https://vtk.org/doc/nightly/html/vtkCellValidator_8h_source.html).
2. Load the dataset in ParaView. Add a ValidateCells filter. Change the coloring to the ValidityState scalar. The meaning is the same as in number 1 above.

### 💻 Which operating system are you using?

Windows

### 📀 Which ANSYS version are you using?

Doesn't matter

### 🐍 Which Python version are you using?

3.9

### 📦 Installed packages

```shell
I validated using ParaView
```