Actually ensure that walls don't get slower than 1 mm/s

CURA-5724

resources/variants/ultimaker2_plus_0.4.inst.cfg

@@ -12,5 +12,5 @@ hardware_type = nozzle
 machine_nozzle_size = 0.4
 machine_nozzle_tip_outer_diameter = 1.05
 speed_wall = =round(speed_print / 1.25, 1)
-speed_wall_0 = =min(speed_wall - 10, 1)
+speed_wall_0 = =max(speed_wall - 10, 1)
 speed_topbottom = =round(speed_print / 2.25, 1)