In a short time, the biennial Olympics of laughter known as Netflix Is a Joke has shined a global spotlight on the L.A. stand-up scene. “You don’t cuss onstage, do you?” — Amy Kaufman Jon Stewart, Greek Theatre, May 3, 8 p.m. — Josh Chesler “LBJ: The Play,” Dynasty Typewriter, May 3, 7 p.m. There’s a lot to unpack in …