The first recordings of Pearl Jam’s 12th studio album go way back. “Some of the songs were recorded two summers ago,” recalled front man Eddie Vedder, 59, in London on the occasion of the release of “Dark Matter.” The most important surviving grunge group then hired producer Andrew Watt to help complete the album, the first since “Gigaton” came out four years ago. Watt, 33, has worked with Elton John, Miley Cyrus and Post Malone. Most recently he collaborated with the Rolling Stones on their celebrated album “Hackney Diamonds.” The Pearl Jam lead singer knows Watt very well, for it was he who …