Kronan said cucumbers have sold out in stores across Iceland. The sales picked up so quickly that the store did not have time to prepare, said Gudrun Adalsteinsdottir, the company’s chief executive. “We are, just literally, eating it up,” joked Gudny Ljosba Hreinsdottir, 29, who runs Wake Up Reykjavik, an Icelandic tourism company with a walking food tour…