FRANKFURT, Germany—The European Central Bank decided Thursday to avoid an abrupt end to its pandemic crisis support for the economy as the new omicron variant of COVID-19 stirs uncertainty about the recovery, despite inflation hitting record highs and the U.S. speeding up its stimulus exit. The cautious approach comes as the 19 European Union member countries using the euro already are seeing the economic rebound slow because of a rise in infections from the delta variant and shortages of parts and raw materials. That has held back an economy that depends on trade and supply chains. The bank confirmed that it will phase out its 1.85 trillion euro ($2.1 trillion) pandemic bond purchase stimulus on schedule next year but will maintain some of the effects by moving part of the purchases to another support program. It also said the pandemic program could be resumed if needed. The bond purchases drive …