message: fix: available endpoint showing specs without drivers
diff: @@ -919,6 +919,9 @@ class DatabaseRestApi(BaseSupersetModelRestApi):
  preferred_databases: List[str] = app.config.get("PREFERRED_DATABASES", [])
  available_databases = []
  for engine_spec, drivers in get_available_engine_specs().items():
  + if not drivers:
  + continue
  +
  payload: Dict[str, Any] = {
  "name": engine_spec.engine_name,
  "engine": engine_spec.engine,
  