Fix REST methods with versioned API (#13977)

Due to changes in behavior with new api_method decorator the
_private attribute is always present for these methods and so
we must explicitly check for whether it is True.

src/middlewared/middlewared/service/core_service.py

@@ -388,7 +388,7 @@ def get_methods(self, app, service, target):
                     continue
 
                 # Skip private methods
-                if hasattr(method, '_private'):
+                if hasattr(method, '_private') and method._private is True:
                     continue
                 if target == 'CLI' and hasattr(method, '_cli_private'):
                     continue