Limit IPv4/IPv6 Prefix length in case of contrail deployment

OpenContrail do not allow configuration of AAP with prefix
length less then 24/120 (IPv4/IPv6) according to bug#1720118

Change-Id: I0a9ca8343d5773174e3a3b3239cb52d9cbeb3bc2
Closes-bug: PROD-21672
diff --git a/_modules/runtest/tempest_sections/network.py b/_modules/runtest/tempest_sections/network.py
index c1baa6a..b9d8cf9 100644
--- a/_modules/runtest/tempest_sections/network.py
+++ b/_modules/runtest/tempest_sections/network.py
@@ -69,7 +69,12 @@
 
     @property
     def project_network_cidr(self):
-        pass
+        contrail_enabled = conditions.BaseRule('*.opencontrail.control.enabled',
+                                               'eq', True, multiple='any')
+        if contrail_enabled.check(self.pillar):
+            return '10.100.0.0/24'
+        else:
+            pass
 
     @property
     def project_network_mask_bits(self):
@@ -77,7 +82,12 @@
 
     @property
     def project_network_v6_cidr(self):
-        pass
+        contrail_enabled = conditions.BaseRule('*.opencontrail.control.enabled',
+                                               'eq', True, multiple='any')
+        if contrail_enabled.check(self.pillar):
+            return '2003::/120'
+        else:
+            pass
 
     @property
     def project_network_v6_mask_bits(self):