NEW YORK — A brazen scheme in which guns — even an AK-47 rifle — were taken onto passenger jets for years in carry-on luggage was described by a Brooklyn prosecutor earlier this week as a terrorism threat that should cause the airline industry to end the practice of letting some workers enter airports without security screening. “I hope this is a wake-up call for the nation,” Brooklyn District Attorney Kenneth Thompson said at a news conference. “This was an egregious breach of our …