Setter function of exported property only called when the value is different from its default

**Your Godot version:** v4.1.2.stable.official [399c9dc39]

**Issue description:**

See this [issue](https://github.com/godotengine/godot/issues/83375) for initial discussion. I though it was a bug.

It should be added that setter functions are not called on default values. If you want to implement some logic for default values, you should handle it on `_init` or `_ready` (and be compatible with non-default ones). Nodes have to be designed from default values.

As possible example, the initial [discussion](https://github.com/godotengine/godot/issues/83375) could be used.

**URL to the documentation page (if already existing):** https://docs.godotengine.org/en/stable/tutorials/scripting/gdscript/gdscript_basics.html#properties-setters-and-getters