### 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)

if (p_to_pos < 0) {
		p_to_pos = occluders.size();
	}
	ERR_FAIL_INDEX(p_to_pos, occluders.size() + 1);
	occluders.insert(p_to_pos, Ref<OccluderPolygon2D>());
}
void TileData::move_occlusion_layer(int p_from_index, int p_to_pos) {