ORLANDO, Fla. — Citing concerns about the credibility of key witnesses against him — including Seminole County’s former tax collector, Joel Greenberg — career Justice Department prosecutors have recommended against charging U.S. Rep. Matt Gaetz with sex trafficking, according to a report. The Washington Post reported Friday that the unnamed prosecutors told their superiors that a conviction of Gaetz, R-Fla., would be “unlikely.” No final decision has been made, according to the Post report, which added “it is rare for such advice to be rejected.” It is now unlikely that Gaetz, who has denied w…