Coldplay is set to launch the next leg of its record-breaking Music of the Spheres world tour this weekend with two sold-out performances at Stanford Stadium, marking the band’s only Northern California appearances this year. The British rock group — singer Chris Martin, guitarist Jonny Buckland, bassist Guy Berryman and drummer Will Champion — is scheduled to perform Saturday, May 31, and Sunday, June 1, in support of its latest album, “Moon…