THE HAGUE, Netherlands—The international team investigating the downing of Malaysia Airlines flight MH17 over eastern Ukraine seven years ago appealed Thursday for Russians in the city of Kursk to come forward with information about the deployment of the missile that investigators say downed the plane, killing all 298 people on board. The call for witnesses included an emotional video featuring the parents of one of the victims, 29-year-old Australian Victor Oreshkin. His mother, Vera Oreshkin, called her son a “gift from God.” “This tragedy has blown a hole in my heart and it will never be filled. Ever,” she says in the video. The appeal comes days before the resumption on Monday of the trial of three Russians and a Ukrainian charged with multiple murders for their alleged role in shooting down on July 17, 2014, the Boeing 777 that was flying from Amsterdam to Kuala Lumpur. The plane was …