### 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)

ERR_FAIL_COND_V_MSG(!tiles.has(p_atlas_coords), TileSetSource::INVALID_TILE_ALTERNATIVE, vformat("TileSetAtlasSource has no tile at %s.", String(p_atlas_coords)));
	ERR_FAIL_COND_V_MSG(p_alternative_id_override >= 0 && tiles[p_atlas_coords].alternatives.has(p_alternative_id_override), TileSetSource::INVALID_TILE_ALTERNATIVE, vformat("Cannot create alternative tile. Another alternative exists with id %d.", p_alternative_id_override));
	int new_alternative_id = p_alternative_id_override >= 0 ? p_alternative_id_override : tiles[p_atlas_coords].next_alternative_id;
	tiles[p_atlas_coords].alternatives[new_alternative_id] = memnew(TileData);
	tiles[p_atlas_coords].alternatives[new_alternative_id]->set_tile_set(tile_set);
	tiles[p_atlas_coords].alternatives[new_alternative_id]->set_allow_transform(true);
	tiles[p_atlas_coords].alternatives[new_alternative_id]->connect("changed", callable_mp((Resource *)this, &TileSetAtlasSource::emit_changed));
	tiles[p_atlas_coords].alternatives[new_alternative_id]->notify_property_list_changed();
	tiles[p_atlas_coords].alternatives_ids.push_back(new_alternative_id);
	tiles[p_atlas_coords].alternatives_ids.sort();
	_compute_next_alternative_id(p_atlas_coords);
	emit_signal(SNAME("changed"));
	return new_alternative_id;
}
void TileSetAtlasSource::remove_alternative_tile(const Vector2i p_atlas_coords, int p_alternative_tile) {
	ERR_FAIL_COND_MSG(!tiles.has(p_atlas_coords), vformat("TileSetAtlasSource has no tile at %s.", String(p_atlas_coords)));
	ERR_FAIL_COND_MSG(!tiles[p_atlas_coords].alternatives.has(p_alternative_tile), vformat("TileSetAtlasSource has no alternative with id %d for tile coords %s.", p_alternative_tile, String(p_atlas_coords)));
	ERR_FAIL_COND_MSG(p_alternative_tile == 0, "Cannot remove the alternative with id 0, the base tile alternative cannot be removed.");
	memdelete(tiles[p_atlas_coords].alternatives[p_alternative_tile]);
	tiles[p_atlas_coords].alternatives.erase(p_alternative_tile);
	tiles[p_atlas_coords].alternatives_ids.erase(p_alternative_tile);
	tiles[p_atlas_coords].alternatives_ids.sort();
	emit_signal(SNAME("changed"));
}
void TileSetAtlasSource::set_alternative_tile_id(const Vector2i p_atlas_coords, int p_alternative_tile, int p_new_id) {