By Francesco Canepa and Balazs Koranyi FRANKFURT (Reuters) -European Central Bank policymakers are gathering on Thursday for what may have become a crisis meeting as Russia’s invasion of Ukraine threatens to derail economic growth in the euro zone and complicate the ECB’s path out of negative interest rates. The ECB’s “informal get-together” was aimed at preparing a decision on March 10 on the likely end of the ECB’s bond-buying stimulus programme, paving the way for the first rate hike in more than a decade to tackle surprisingly high inflation. But Russia’s invasion of Ukraine overnight has …