FRANKFURT (Reuters) – Siemens Energy should buy the rest of struggling wind turbine division Siemens Gamesa, Union Investment said on Monday, the first such demand by a major investor since a recent profit warning and leadership change. Siemens Gamesa last month issued its third profit warning in nine months, a move that has led parent Siemens Energy to send board member Jochen Eickholt to take charge at the unit from March to become its third CEO in 18 months. At the root of the problem lie supply chain issues and a delayed ramp up of Siemens Gamesa’s next generation of onshore wind turbine, …