Currently there is no way to block search indexes. Have a look at adding a new setting in order to block search engine crawling which will output the robots.txt file as
User-agent: * Disallow: /
The Sitemapseo has a similar problem, to disable the sitemap.xml you need to CommonSettings.SitemapEnabled which will hide your Sitemap html page which should not be effected by removing crawler access.
This will prevent google from indexing test sites.