a716685f2f
d1049f6082 translated the logic from the `int8` to `float`
conversion incorrectly. Previously the data was extracted to an integer
array (multiplied by 254) first then translated to a float VBO (and
divided by 255). I think conceptually the special `1.0/255` value isn't
necessary because the "optimal display edges" area already taken into
account for the creation of the index buffer. But as a quick fix, just
fix the factor to be the same as before.
Pull Request: https://projects.blender.org/blender/blender/pulls/126290