CORD-1913: Restore execution of custom service save() methods in attics

Change-Id: Ifcb692103f40cc254da523a23f595ad7f36c226c
(cherry picked from commit 9545fd8c5a0aaccdf042811e9ab862d3dc7cbbf8)
diff --git a/xos/attic/volttenant_model.py b/xos/attic/volttenant_model.py
index c7a3420..d2c714b 100644
--- a/xos/attic/volttenant_model.py
+++ b/xos/attic/volttenant_model.py
@@ -57,7 +57,7 @@
             return roots[0]
     return None
 
-def save(self, *args, **kwargs):
+def __xos_save_base(self, *args, **kwargs):
     if not self.creator:
         if not getattr(self, "caller", None):
             # caller must be set when creating a vCPE since it creates a slice
@@ -66,4 +66,4 @@
         if not self.creator:
             raise XOSProgrammingError("VOLTTenant's self.creator was not set")
 
-    super(VOLTTenant, self).save(*args, **kwargs)
+    return False