EXCLUSIVE: I’ve learned that Netflix has opted not to proceed with a second season of Baz Luhrmann's ambitious musical drama The Get Down. The decision comes after the second six-episode part of Season 1 was released last month. It is a rare Netflix original series not to get a second season. The hip-hop-themed drama, set in the South Bronx section of New York City in the late 1970s, was among Netflix’s most expensive shows, with the 12-episode first season costing about…