It turns out that “becoming a test account” just means joining the Facebook Test Account Network.  So all you have to do is leave that network in order to get all of your contacts back.  You can do this by clicking “Account” in the upper right of the site.  Under that, click “Account Settings”.  Once there, go to the second tab that says “Networks”.  You should see the Test Account network listed there with a link to “leave network”. Once you leave, all of your contacts and content will be restored.