### 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)

p_peering_bit == TileSet::CELL_NEIGHBOR_BOTTOM_SIDE ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_BOTTOM_LEFT_SIDE ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_TOP_LEFT_SIDE ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_TOP_SIDE ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_TOP_RIGHT_SIDE) {
					return true;
				}
			}
			if (p_terrain_mode == TileSet::TERRAIN_MODE_MATCH_CORNERS_AND_SIDES || p_terrain_mode == TileSet::TERRAIN_MODE_MATCH_CORNERS) {
				if (p_peering_bit == TileSet::CELL_NEIGHBOR_RIGHT_CORNER ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_BOTTOM_RIGHT_CORNER ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_BOTTOM_LEFT_CORNER ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_LEFT_CORNER ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_TOP_LEFT_CORNER ||
						p_peering_bit == TileSet::CELL_NEIGHBOR_TOP_RIGHT_CORNER) {
					return true;
				}
			}
		}
	}
	return false;
}
bool TileSet::is_valid_terrain_peering_bit(int p_terrain_set, TileSet::CellNeighbor p_peering_bit) const {
	if (p_terrain_set < 0 || p_terrain_set >= get_terrain_sets_count()) {
		return false;
	}
	TileSet::TerrainMode terrain_mode = get_terrain_set_mode(p_terrain_set);
	return is_valid_terrain_peering_bit_for_mode(terrain_mode, p_peering_bit);
}
int TileSet::get_navigation_layers_count() const {