Grease Pencil: Reduce size of primary gizmo on line primitives

Reduce size of last endpoint gizmo on line primitives `size_primary` 8.0f
to be the same size of `size_tertiary` 3.0f. Circle and Box primitives are
unchanged as they don't have endpoints and a bigger gizmo doesn't affect
visibility. Motivation for this change is to increase visibility of the endpoint
while drawing since the default is too big for these type of lines and it
blocks the view of it.

Pull Request: https://projects.blender.org/blender/blender/pulls/135658

source/blender/editors/grease_pencil/intern/grease_pencil_primitive.cc

@@ -245,7 +245,7 @@ static void control_point_colors_and_sizes(const PrimitiveToolOperation &ptd,
     }
 
     colors.last() = color_gizmo_primary;
-    sizes.last() = size_primary;
+    sizes.last() = size_tertiary;
 
     if (ELEM(ptd.type, PrimitiveType::Line, PrimitiveType::Polyline)) {
       colors.last(1) = color_gizmo_secondary;