[FIX] utm: apply legacy kanban style

For the few remaining uses of the legacy kanban view, the utm addon
style wasn't applied.

This is due to the fact that the legacy kanban view does not have a
"o_kanban_renderer" class.

Part-of: odoo/odoo#94952

addons/utm/static/src/scss/utm_views.scss

@@ -1,4 +1,4 @@
-.o_kanban_renderer.o_utm_kanban {
+.o_utm_kanban {
     .o_kanban_group {
         padding: 0 ($grid-gutter-width * .25) $grid-gutter-width;