Don't change the prime tower size based on prime tower enable

The prime tower is properly disabled in the engine nowadays if prime_tower_enable is false.

resources/definitions/fdmprinter.def.json

@@ -3637,7 +3637,6 @@
                     "unit": "mm",
                     "enabled": "resolveOrValue('prime_tower_enable')",
                     "default_value": 15,
-                    "value": "15 if resolveOrValue('prime_tower_enable') else 0",
                     "resolve": "max(extruderValues('prime_tower_size'))",
                     "minimum_value": "0",
                     "maximum_value": "min(0.5 * machine_width, 0.5 * machine_depth)",