By Tom Balmforth and Max Hunder KYIV (Reuters) – Russian forces in Ukraine will focus on trying to seize all of the Donetsk region, having forced Ukrainian troops to withdraw from the last major city under their control in the neighbouring Luhansk region, the governor of Luhansk said on Monday. After abandoning an assault on Kyiv, the Ukrainian capital, during the early weeks of the war, Russia concentrated its military operation on the industrial Donbas heartland that comprises the Luhansk and Donetsk regions, where Moscow-backed separatist proxies have been fighting Ukraine since 2014. Russi…