Sometimes you need to go home again. In Metallica’s case, it was the band’s 2008 album, “Death Magnetic,” that brought the band back to its roots so it could move forward. In tandem with producer Rick Rubin, the icon-whisperer who reminds legends what they do best in mid- to late-career albums (see his work with Johnny Cash, Jay-Z, Tom Petty and Black Sabbath, among others), Metallica made its ninth studio album sound like a recording it could have released amid its 1980s run of classics.