Louis Lortie, who was scheduled to perform all three of Tchaikovsky’s piano concertos this weekend, has the flu. In his absence, Conrad Tao will perform Tchaikovsky’s Piano Concerto No. 1. The Utah Symphony, under music director Thierry Fischer, will perform Tchaikovsky’s “Sleeping Beauty” Suite and “Capriccio Italien” in place of the other, seldom-performed concertos. Arnold Schoenberg’s imaginary film score, “Accompaniment to a Cinematographic Scene,” rounds out the program.