IT was the society wedding of the year. On June 7, billionaire Hugh Grosvenor, the 7th Duke of Westminster, wed Olivia Henson, 31, a food company account manager, at England’s historic Chester Cathedral. On hand to help his childhood friend on his big day, future king Prince William. Noticeably absent? Hugh’s other royal pal, Prince Harry. “Hugh’s family has been close to the royals for generations,” a source tells Star of the godfather to William’s son Prince George, 10, and Harry’s older child, Prince Archie, 5. But with the brothers still feuding, it was clear both couldn’t attend, lest their drama distract from the pomp — especially after William, 41, was tapped to be an usher. Although Harry and his wife, Meghan Markle, were invited, the source explains, “a delicate…