(Corrects final paragraph to remove reference to oil products) FRANKFURT (Reuters) -Germany has activated the first stage of an emergency plan to manage gas supplies in Europe’s largest economy in preparation for a possible disruption or halt in natural gas supplies from Russia. Russia accounted for 55% of Germany’s gas imports in 2021 and 40% in the first quarter of 2022. Economy Minister Robert Habeck has said Germany will not achieve full independence from Russian supplies before mid-2024. WHAT’S THE PROBLEM? Moscow said last week it would draw up a mechanism by March 31 under which so-call…