Google began directing customers looking for the Nexus 4 in the U.S. to T-Mobile, since Google itself hasn’t had stock for quite a while now. T-Mobile charges $199 on a 2-year contract, after a $50 mail-in rebate. That’s not nearly as good a deal as the $300 Google was charging off-contract, but T-Mobile is now sold out only hours after Google started pointing shoppers in…