Create default network for server advance scenario tests

Previously when fixing this bug for API tests,
we thought it cannot happen in scenario tests
with same reason as scenario base class do fetch
the specific network from neutron to pass it t nova
for creating the server.

But when 'CONF.network.port_vnic_type' and
'CONF.network.port_profile' are not configured in Tempest
then Tempest scenario manager does not fetch the network
from neutron.
- fec2c93cdc/tempest/scenario/manager.py (L242)

In that case, tenant network is used, which is not present
as scenario manager does not create the default network
resource for credential and tenant.

- fec2c93cdc/tempest/scenario/manager.py (L298)

This commit let server advance test (which is failing for multiple network
erorr) to create the default network which will be used to pass to the
nova API request while creating the test server.

Related-Bug: #1844568
Change-Id: I5a73a4f25f9092a4cdddcaf86f9ff2c89720409e

tempest/scenario/test_server_advanced_ops.py

@@ -37,7 +37,7 @@ class TestServerAdvancedOps(manager.ScenarioTest):
 
     @classmethod
     def setup_credentials(cls):
-        cls.set_network_resources()
+        cls.set_network_resources(network=True, subnet=True)
         super(TestServerAdvancedOps, cls).setup_credentials()
 
     @decorators.attr(type='slow')