### Godot version

v4.0.3.stable.mono.official [5222a99f5]

### System information

macOS Monterey 12.6.6 (21G646)

### Issue description

When creating a tileset by code with custom data layers, removing a layer with `remove_custom_data_layer` does not update the name-to-layer mapping; `get_custom_data_layer_by_name` will continue to return that layer's original index.

This has a downstream effect of causing TileData objects attempting to use `get_custom_data('Layer B')` to return invalid data (whatever custom data is now in Layer B's old index; e.g. Layer C).

I would expect that after using `remove_custom_data_layer`, I would be able to still use `get_custom_data_layer_by_name` on that tileset.

### Steps to reproduce

Run this code to see that getting Layer B by name after removing the first layer continues to return its original index (1) when in reality it is now at index 0.
```
	var tileset:TileSet = TileSet.new()

	tileset.add_custom_data_layer()
	tileset.set_custom_data_layer_name(0, 'Layer A')
	tileset.set_custom_data_layer_type(0, TYPE_INT)

	tileset.add_custom_data_layer()
	tileset.set_custom_data_layer_name(1, 'Layer B')
	tileset.set_custom_data_layer_type(1, TYPE_STRING)

	print('Layer index 0 name : ', tileset.get_custom_data_layer_name(0)) # Layer A
	print('Layer index 1 name : ', tileset.get_custom_data_layer_name(1)) # Layer B
	print('Layer B is on index : ', tileset.get_custom_data_layer_by_name("Layer B")) # 1

	print('----- removing custom data layer 0 -----')
	tileset.remove_custom_data_layer(0)

	print('Layer index 0 name : ', tileset.get_custom_data_layer_name(0)) # Layer B
	print('Layer index 1 name : ', tileset.get_custom_data_layer_name(1)) # prints an error, as expected
	print('Layer B is on index : ', tileset.get_custom_data_layer_by_name("Layer B")) # returns 1 still! should return 0.
```

### Minimal reproduction project

[RemoveCustomDataLayer.zip](https://github.com/godotengine/godot/files/11804762/RemoveCustomDataLayer.zip)

Array from;
	from.push_back(p_source_from);
	from.push_back(p_coords_from);
	from.push_back(p_alternative_from);
	return alternative_level_proxies.has(from);
}
void TileSet::remove_alternative_level_tile_proxy(int p_source_from, Vector2i p_coords_from, int p_alternative_from) {
	Array from;
	from.push_back(p_source_from);
	from.push_back(p_coords_from);
	from.push_back(p_alternative_from);
	ERR_FAIL_COND(!alternative_level_proxies.has(from));
	alternative_level_proxies.erase(from);
	emit_changed();
}
Array TileSet::get_source_level_tile_proxies() const {
	Array output;
	for (const KeyValue<int, int> &E : source_level_proxies) {
		Array proxy;
		proxy.push_back(E.key);
		proxy.push_back(E.value);
		output.push_back(proxy);
	}
	return output;
}
Array TileSet::get_coords_level_tile_proxies() const {