How does a celebrated, tight-knit partnership keep the luster of its brand as it changes its personnel? Another of Silicon Valley’s most successful investors at one of its marquee venture capital firms, Benchmark, is choosing not to sign up again as a partner. Matt Cohler, a board member at Uber who is seen as one of the most prescient and precocious investors in the sector, won’t be a part of Benchmark’s next fund, according to a new regulatory disclosure on Monday.