Clears existing update caches for plugins, themes, and core.

function wp_clean_update_cache() {
	if ( function_exists( 'wp_clean_plugins_cache' ) ) {
		wp_clean_plugins_cache();
	} else {
		delete_site_transient( 'update_plugins' );
	}

	wp_clean_themes_cache();

	delete_site_transient( 'update_core' );
}