FRANKFURT—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 eurozone and complicate the ECB’s path out of negative interest rates. The ECB’s policymaking Governing Council had been due to gather in Paris on Thursday for an “informal get-together.” This was aimed at preparing a decision on March 10 on the likely end of the ECB’s bond-buying stimulus program and pave 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 changed the picture by raising the prospect of higher energy costs, financial turmoil, and lower trade for the eurozone, which relies on Russian gas for 40 percent of its needs. “In my view it is going to have a short-term inflationary effect—that is prices will increase due …