Remove old-style pico demo (#701)

Author: PieterOlivier

rascal-lsp/src/main/rascal/library/demo/lang/pico/OldStyleLanguageServer.rsc

@@ -52,7 +52,7 @@ parameterizedDescribe(function (errorRecovery: boolean) {
     async function loadPico() {
         const repl = new RascalREPL(bench, driver);
         await repl.start();
-        await repl.execute("import demo::lang::pico::OldStyleLanguageServer;");
+        await repl.execute("import demo::lang::pico::LanguageServer;");
 
         // If Pico was registered before as part of another series of tests,
         // then it needs to be unregistered first (because error recovery