Makes "segmentation_id" configurable

We should add the segmentation_id as tempest option,
so that it can be changed to match the deployment if needed.

Change-Id: I42bea9217462226e8650e55997449e1cc05f085c
Related-Prod: https://mirantis.jira.com/browse/PRODX-43703
(cherry picked from commit 8fdbc7bbe3231ce01ee2bfe44435744a25746c7f)
diff --git a/neutron_tempest_plugin/scenario/test_dns_integration.py b/neutron_tempest_plugin/scenario/test_dns_integration.py
index f7ab6ef..7fce12f 100644
--- a/neutron_tempest_plugin/scenario/test_dns_integration.py
+++ b/neutron_tempest_plugin/scenario/test_dns_integration.py
@@ -176,11 +176,10 @@
     @classmethod
     def resource_setup(cls):
         super(DNSIntegrationAdminTests, cls).resource_setup()
-        # TODO(jh): We should add the segmentation_id as tempest option
-        # so that it can be changed to match the deployment if needed
-        cls.network2 = cls.create_network(dns_domain=cls.zone['name'],
-                provider_network_type='vxlan',
-                provider_segmentation_id=12345)
+        segmentation_id = CONF.designate_feature_enabled.segmentation_id
+        cls.network2 = cls.create_network(
+            dns_domain=cls.zone['name'], provider_network_type='vxlan',
+            provider_segmentation_id=segmentation_id)
         cls.subnet2 = cls.create_subnet(cls.network2)
 
     def _verify_dns_assignment(self, port):