Contour's `showGeometry: false` not hiding HiddenLines on geomertry

[Ellord207]

Describe the bug When using ContourDisplay with the HiddenLine render mode with a Contour's showGeometry property set to false, there will still be lines for the geometry alongside the contour lines. In my exploration, I could not find a way to hide just the "hiddenLines" and still show the ContourLines.

I mentioned a secondary path/bug I attempted in the Additional Context section to work around this limitation, which would be an acceptable solution criteria. Please see it.

To Reproduce

1. Create a ViewState with ContourDisplay in SmoothShading RenderMode
2. Ensure that the Contour's showGeometry flag is set to false
3. Observe only the ContourDisplay lines are visible on the element
4. Set RenderMode to HiddenLine
5. (Bug) Observe both HiddenLine lines and ContourDisplay lines on the element

Expected behavior Only see the ContourDisplay lines on the element

Screenshots If applicable, add screenshots to help explain your problem.

The highlighted element is included is included in a ContourGroup with the showGeometry flag set to false. The solid line are from HiddenLine and the dashed lines are from ContourDisplay.

Desktop (please complete the applicable information):

• OS: windows 11
• @itwin/core-frontend 5.1.8

Additional context Feasibility Testing still needs to be done on if this ContourDisplay will work for our workflow. This item's priority should be considered with the resolution of this discussion: https://github.com/iTwin/itwinjs-core/issues/8141

I would expect there to be some way to achieve the result of showing the ContourDisplay Lines and not the HiddenLine geometry. For example, I noticed a SubCategory's FeatureOverride does not effect the color of the contour lines, but does effect the transparency of both the HiddenLines and ContourDisplay. The fact that ContourLines are effected by the transparency at all seems like it could be considered a different bug. Please let me know if you want me to file this issue separately.

Talked with @markschlosseratbentley about this already. Can provide iModel to reproduce the issue if requested.