Do not set VRF assign rules for right interfaces of nat instances

We are planning not to link service RI with the primary RI of the
right networks of in-network-nat instances. We should also not
set VRF assign rules.

Change-Id: I11ad075a2d91e5da18094612a2c5935366197c94
Partial-Bug: 1554175
Related-Bug: 1562200

src/config/schema-transformer/to_bgp.py

@@ -2405,9 +2405,14 @@ def recreate_vrf_assign_table(self):
         if smode not in ['in-network', 'in-network-nat']:
             return
 
+        if smode == 'in-network-nat' and self.service_interface_type == 'right':
+            vn_policies = []
+        else:
+            vn_policies = vn.policies
+
         policy_rule_count = 0
         si_name = vm_obj.service_instance
-        for policy_name in vn.policies:
+        for policy_name in vn_policies:
             policy = NetworkPolicyST.get(policy_name)
             if policy is None:
                 continue