CHICAGO (AP) — To open its celebration of its 100th season, the NFL got a throwback to, well, the 1920s. You know, one of those knock-down, dragged-out defensive confrontations that ends up 10-3. That’s the score the Green Bay Packers beat the Chicago Bears by on Thursday night. And while it was ugly on offense, likely in great part due to the lack of action so many regulars on that side of the…