ALLEN PARK, Mich. — Jared Goff has been here and done this before. He has been there and done that, too. But this isn’t about that, he insists. This is about being the Detroit Lions’ quarterback, not the former Los Angeles Rams quarterback, and even as his two worlds collide this week — the past and the present — for Goff there’s no ambiguity here. “I mean, obviously, there’s a personal connection there,” Goff said Wednesday as the Lions returned to the practice field ahead of Sunday night’s NFC wild-card matchup against the Rams at Ford Field. “But, no, I so badly want to win a playoff game f…