Hide the contact shadow property as it often looks broken
Created by: Calinou
The property can still be adjusted by setting its value in a script, but it's no longer exposed in the editor. There are significant bugs that prevent its widespread use anyway.
This might be a bit controversial, but time has showed yet again that people are often confused by this feature
We could also remove all code related to contact shadows, but it's more work and might make the Vulkan rebase more difficult.