Fix: GPv3: Wrong cursor radius for Tint tool and Weight Paint tools
The brush cursor size (the circle in the viewport) of the Tint tool and
the Weight Paint tools didn't match the brush radius, because:
- The radius unit `Scene` calculation was also applied to the Tint tool
brush, while it's only relevant for Draw brushes.
- The Weight Paint tools use unified paint settings and the Draw tool
doesn't any more since #122886, causing a mismatch in cursor size.
In this PR the cursor size is fixed.
Pull Request: https://projects.blender.org/blender/blender/pulls/124100
e9da9a90bb