Remove os.exit from the Lua secure sandbox (#5090)

os.exit will exit not using proper resource liberation paths.

Mods should call the proper exit mod using our API

src/script/cpp_api/s_security.cpp

@@ -99,7 +99,6 @@ void ScriptApiSecurity::initializeSecurity()
 		"clock",
 		"date",
 		"difftime",
-		"exit",
 		"getenv",
 		"setlocale",
 		"time",