OS-7570. Fixed Azure discovery for intances without sg (#808)

## Related issue number

OS-7570

## Checklist

* [x] The pull request title is a good summary of the changes
* [ ] Unit tests for the changes exist
* [ ] New and existing unit tests pass locally

tools/cloud_adapter/clouds/azure.py

@@ -611,7 +611,8 @@ def _get_nics_by_instance(self, vm, return_all=True):
 
     def _get_sgs_by_instance(self, vm):
         nics = self._get_nics_by_instance(vm, return_all=True)
-        sgs_ids = set(nic.network_security_group.id for nic in nics)
+        sgs_ids = set(nic.network_security_group.id for nic in nics
+                      if hasattr(nic.network_security_group, 'id'))
         return list(sgs_ids)
 
     def _get_vnet_id_by_instance(self, vm):