SEATTLE—Boeing’s newest version of the 737 Max jetliner completed its first test flight Friday in a move that the company hopes will signal improving fortunes for its most important plane. A few hundred employees watched the plane take off from Renton, Washington. As is typical for a first test flight of a new plane, the only people on board were the two pilots, Jennifer Henderson and Jim Webb. The pilots flew for about 2 1/2 hours over Washington state and did a touch-and-go maneuver at an airport near Moses Lake, Washington, before returning to land at Boeing Field in Seattle, about 7 miles from where they left. The Max 10 is a slightly larger version of Max jets that are already flying. It is designed to seat up to 230 passengers and compete with the A321neo from European rival Airbus. Chicago-based Boeing expects to begin delivering Max 10s to airlines …