### 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)

overlap = 0.25;
				break;
			case TileSet::TILE_SHAPE_HALF_OFFSET_SQUARE:
				overlap = 0.0;
				break;
			default:
				break;
		}
		if (terrain_mode == TileSet::TERRAIN_MODE_MATCH_CORNERS_AND_SIDES) {
			return _get_half_offset_corner_or_side_terrain_peering_bit_polygon(tile_size, overlap, tile_offset_axis, p_bit);
		} else if (terrain_mode == TileSet::TERRAIN_MODE_MATCH_CORNERS) {
			return _get_half_offset_corner_terrain_peering_bit_polygon(tile_size, overlap, tile_offset_axis, p_bit);
		} else { 
			return _get_half_offset_side_terrain_peering_bit_polygon(tile_size, overlap, tile_offset_axis, p_bit);
		}
	}
}
#define TERRAIN_ALPHA 0.6
void TileSet::draw_terrains(CanvasItem *p_canvas_item, Transform2D p_transform, const TileData *p_tile_data) {
	ERR_FAIL_NULL(p_tile_data);
	if (terrain_bits_meshes_dirty) {
		
		terrain_peering_bits_meshes.clear();
		for (int terrain_mode_index = 0; terrain_mode_index < 3; terrain_mode_index++) {
			TerrainMode terrain_mode = TerrainMode(terrain_mode_index);
			
			Vector<Vector2> polygon;
			if (tile_shape == TileSet::TILE_SHAPE_SQUARE) {
				polygon = _get_square_terrain_polygon(tile_size);
			} else if (tile_shape == TileSet::TILE_SHAPE_ISOMETRIC) {