By Humeyra Pamuk and Anne Kauranen MADRID/HELSINKI (Reuters) -NATO ally Turkey lifted its veto over Finland and Sweden’s bid to join the Western alliance on Tuesday after the three nations agreed to protect each other’s security, ending a weeks-long drama that tested allied unity against Russia’s invasion of Ukraine. The breakthrough came after four hours of talks just before a NATO summit began in Madrid, averting an embarrassing impasse at the gathering of 30 leaders that aims to show resolve against Russia, now seen by the U.S.-led alliance as a direct security threat rather than a possible…