By Natalia Zinets KYIV/MARIUPOL, Ukraine (Reuters) – The Ukrainian unit holed up beneath the Azovstal steelworks in Mariupol said on Monday its garrison was fulfilling orders to save the lives of troops, an apparent sign that the longest and bloodiest battle of the Ukraine war had come to an end. Reuters saw about a dozen buses apparently carrying Ukrainian fighters leaving the plant on Monday. It was not possible to determine how many people were aboard. Some 600 fighters have been estimated to be inside the vast Soviet-era plant, including dozens of wounded. “In order to save lives, the enti…