### 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)

per_terrain_pattern_tiles[terrain_set][terrains_pattern].insert(cell);
							}
							
							for (int i = 0; i < TileSet::CELL_NEIGHBOR_MAX; i++) {
								CellNeighbor bit = CellNeighbor(i);
								if (is_valid_terrain_peering_bit(terrain_set, bit)) {
									int terrain = terrains_pattern.get_terrain_peering_bit(bit);
									if (terrain >= 0) {
										per_terrain_pattern_tiles[terrain_set][terrains_pattern].insert(cell);
									}
								}
							}
						}
					}
				}
			}
		}
		
		for (int i = 0; i < terrain_sets.size(); i++) {
			TileSet::TerrainsPattern empty_pattern(this, i);
			TileMapCell empty_cell;
			empty_cell.source_id = TileSet::INVALID_SOURCE;
			empty_cell.set_atlas_coords(TileSetSource::INVALID_ATLAS_COORDS);
			empty_cell.alternative_tile = TileSetSource::INVALID_TILE_ALTERNATIVE;
			per_terrain_pattern_tiles[i][empty_pattern].insert(empty_cell);
		}
		terrains_cache_dirty = false;
	}
}
void TileSet::_compute_next_source_id() {