Setup resources with network for scenario tests

for all scenario tests, setup network resources with
- network
- subnet with dhcp
- router

Related-Prod: PRODX-26330
Related-Prod: PRODX-26471
Change-Id: Ia10a987eac24c576403f45c2888ae951fac4fcda
diff --git a/barbican_tempest_plugin/tests/scenario/manager.py b/barbican_tempest_plugin/tests/scenario/manager.py
index f09bc87..5ee8f21 100644
--- a/barbican_tempest_plugin/tests/scenario/manager.py
+++ b/barbican_tempest_plugin/tests/scenario/manager.py
@@ -30,7 +30,10 @@
 
 # we inherit from NetworkScenarioTest since some test cases need access to
 # check_*_connectivity methods to validate instances are up and accessible
-class ScenarioTest(manager.NetworkScenarioTest):
+# we also inherit from ScenarioTestWithNetwork to get the networking resources
+# pre-setup for us by setup_credentials (network, subnet with dhcp, router)
+class ScenarioTest(manager.ScenarioTestWithNetwork,
+                   manager.NetworkScenarioTest):
     """Base class for scenario tests. Uses tempest own clients. """
     # ## Test functions library
     #