allow bridge speeds to be lower then cool_min_speed

With PP-71 the cool_min_speed is increased to a high values in case the lift_head is enabled. This causes the bridge_speeds to be lower then the cool_min_speed. Which is no problem, so the limit can be removed.
PP-71 / CURA-10211

(cherry picked from commit 6d0be0191340a3d4888662812ee1033305c1196b)

resources/definitions/fdmprinter.def.json

@@ -7762,7 +7762,7 @@
                     "description": "The speed at which the bridge walls are printed.",
                     "unit": "mm/s",
                     "type": "float",
-                    "minimum_value": "cool_min_speed",
+                    "minimum_value": "0",
                     "maximum_value": "math.sqrt(machine_max_feedrate_x ** 2 + machine_max_feedrate_y ** 2)",
                     "maximum_value_warning": "300",
                     "default_value": 15,
@@ -7789,7 +7789,7 @@
                     "description": "The speed at which bridge skin regions are printed.",
                     "unit": "mm/s",
                     "type": "float",
-                    "minimum_value": "cool_min_speed",
+                    "minimum_value": "0",
                     "maximum_value": "math.sqrt(machine_max_feedrate_x ** 2 + machine_max_feedrate_y ** 2)",
                     "maximum_value_warning": "300",
                     "default_value": 15,
@@ -7850,7 +7850,7 @@
                     "description": "Print speed to use when printing the second bridge skin layer.",
                     "unit": "mm/s",
                     "type": "float",
-                    "minimum_value": "cool_min_speed",
+                    "minimum_value": "0",
                     "maximum_value": "math.sqrt(machine_max_feedrate_x ** 2 + machine_max_feedrate_y ** 2)",
                     "maximum_value_warning": "300",
                     "default_value": 25,
@@ -7902,7 +7902,7 @@
                     "description": "Print speed to use when printing the third bridge skin layer.",
                     "unit": "mm/s",
                     "type": "float",
-                    "minimum_value": "cool_min_speed",
+                    "minimum_value": "0",
                     "maximum_value": "math.sqrt(machine_max_feedrate_x ** 2 + machine_max_feedrate_y ** 2)",
                     "maximum_value_warning": "300",
                     "default_value": 15,