SAN DIEGO — Souplantation, the popular buffet-style dining brand founded in San Diego 42 years ago, is closing all of its restaurants permanently, a casualty of the coronavirus pandemic that is likely to be the death knell for all self-serve eateries.The permanent shuttering of the 97 restaurants, including 44 in California, was announced Thursday following weeks of efforts to salvage San Diego-based Garden Fresh Restaurants, the parent company of Souplantation and Sweet Tomatoes, which operates outside of Southern California. The closing will mean lost jobs for 4,400 employees.“The FDA had pr…