CBS: "Houston Knights," an hour drama, stars Michael Pare as a Chicago policeman threatened by the Mob who goes to Houston and becomes partners with good ol' boy Michael Beck. . . . Lindsay Wagner shows her flair for sitcomedy as a woman in her 30s who gives up her law practice to become an artist. You might call the ex-Bionic woman a "Late Bloomer"-which is the name of the series. . . . MTM Prod. presents "The Popcorn Kid," about five Kansas City teens holding down after-school jobs in a local movie theater. . . . Con artist Margot Kidder goes to work for TV producer James Read and they become investigative reporters in "Shell Game," a half-hour comedy-drama. . . . The news magazine "West 57th" will return for a regular run. . . . George Hamilton is a burned-out James Bond type in an hour comedy/drama entitled "Spies." . . .