LONDON (Reuters) – China’s Tsingshan Holding Group has reached an agreement with banks under which they will not make margin calls on or close out the producer’s nickel positions on the London Metal Exchange (LME), the company said on Monday, a move sources said should help calm the market. During the standstill agreement, the company and banks will discuss a standby secured liquidity facility, Tsingshan said. It did not provide any other details, such as how long the standstill period would last. Nickel prices on the LME jumped to record highs above $100,000 a tonne on March 8 as Tsingshan bo…