The price of halal meat exports skyrocketed after Sen. Bob Menendez (D-NJ) helped give one company, led by a Coptic Christian, a monopoly in the market, a government witness testified Friday. James Bret Tate, a U.S. diplomat based in Cairo, told a Manhattan federal jury how halal meat certification ended up in the hands of a single company run by Menendez’s friend and co-defendant Wael Hana. The meat market had been operated by several companie…