This patch removes the Alpha option in the Map UV node. That's because
it currently only has a marginal effect on the result of the node and is
unnoticeable to the user.
The alpha option was supposed to darken the edges of the object that has
the UVs by attenuating the result according to the Laplacian of UV
coordinates. But the attenuation factor was too small to be noticeable.
This option was probably added when UV passes had no anti-aliased alpha
and was therefore needed to smooth the transition at the edges probably.
We asked for user feedback and got feedback from the studio, and it seem
the option is mostly unused.
Pull Request: https://projects.blender.org/blender/blender/pulls/138116
682ab26994