Fix cell coloring for thick lines on apple silicon

- address paraview/paraview#22594
- address paraview/paraview#21832
- Thick lines were drawn by expanding a line to 2 triangles stacked on their longest side using a geometry shader. When coloring by cell scalars, this worked everywhere except on apple silicon.
- There seems to be a bug related to geometry shaders in Apple's OpenGL driver that caused thick lines to not correctly pick up cell colors.
- It looks like the value written to `gl_PrimitiveID` is overwritten implicitly by `EmitVertex` and incremented each time a vertex is emitted from the geometry shader.
- This commit works around it by fixing the usage of `gl_PrimitiveID` in fragment shader when drawing thick lines.