By Valentina Za MILAN (Reuters) -Italy’s Intesa Sanpaolo said on Monday it was selling its entire 5.1% stake in Nexi, in an effort to cash in on a recent rally in shares of the payments group. Intesa agreed to a 25-year partnership as part of the Italian bank’s 2020 sale of its retailers’ payments business to Nexi. Intesa said in a statement that the sale of the stake would have no impact on its strategic partnership with Nexi. Under the 2020 deal, which yielded Italy’s biggest bank a capital gain of 1.1 billion euros, Intesa took a 9.9% stake in Nexi. Intesa’s stake got smaller as a proportio…