### Godot version

4.01

### System information

Windows 10

### Issue description

It seems a tiles Custom Data is cleared/not set when "Local to Scene" is enabled for the TileMap in the Resource section. At least the custom data isn't set by the time of the _ready function in the script attached to the TileMap.

### Steps to reproduce

create TileMap and tileset with custom data and attached script. in _ready method attempt to read custom data from a used cell. 

In Attached project run it. It will print_debug if it found custom data or not. "Local to Scene" is enabled so it will not find the custom data.

### Minimal reproduction project

[TileMapCustomDataLocalBugReproduce.zip](https://github.com/godotengine/godot/files/11470771/TileMapCustomDataLocalBugReproduce.zip)

for (const KeyValue<Vector2i, TileMapCell> &E : pattern) {
		Vector2i coords = E.key;
		if (p_size.x <= coords.x || p_size.y <= coords.y) {
			ERR_FAIL_MSG(vformat("Cannot set pattern size to %s, it contains a tile at %s. Size can only be increased.", p_size, coords));
		};
	}
	size = p_size;
	emit_changed();
}
bool TileMapPattern::is_empty() const {
	return pattern.is_empty();
};
void TileMapPattern::clear() {
	size = Size2i();
	pattern.clear();
	emit_changed();
};
bool TileMapPattern::_set(const StringName &p_name, const Variant &p_value) {
	if (p_name == "tile_data") {
		if (p_value.is_array()) {
			_set_tile_data(p_value);
			return true;
		}
		return false;
	}
	return false;
}
bool TileMapPattern::_get(const StringName &p_name, Variant &r_ret) const {