“The Righteous Gemstones,” a show about a family of self-obsessed televangelists, ended its third season with a rapture and has been renewed by HBO for a fourth season. It has a lot in common with HBO’s “Succession,” which concluded before its return. Both series center around a dynasty of self-obsessed public figures — the founding patriarch and his immature adult children — and the consequences they have on American life. If “Succession” felt like eating your vegetables, then “The Righteous Gemstones” is like the edible sides you have at your local bar: predictable rhythms, but there’s no doubt you’ll instantly indulge in it.