LONDON — Donald Trump’s tariffs have already hammered Britain’s embattled steelmakers — but the EU’s looming trade protection measures could hit them harder still. The EU is preparing to reduce foreign steel quotas by almost half as part of new measures set to be officially proposed on Tuesday. That’s a problem for Britain’s metal manufacturers, who export half of what they produce to the EU — their largest export market. The moves echo a French proposal backed in July by Europe’s steel lobby