By Sruthi Shankar and Susan Mathew (Reuters) -European shares hit more than one-year lows on Thursday as slowing euro zone business activity heightened growth worries, while German shares dropped 1.8% after the country triggered the “alarm stage” of its emergency gas plan. The continent-wide STOXX 600 index dropped 0.8%, with euro zone banks shedding 4.5%. Euro zone bond yields also slid as did the euro. [GVD/EUR] The German DAX slid to over three-month lows as falling Russian supplies prompted Thursday’s move – the latest escalation in a standoff between Europe and Moscow since the Russian in…