[fwaas] Remove _create_subnet & setup_clients

As tempest.scenario.manager was announced stable interface in Tempest
27.0.0[1] it can be now reused in plugins.

Replaced methods:
    * _create_subnet
    * setup_clients

Etherpad concerning this effort:
https://etherpad.opendev.org/p/tempest-scenario-manager-cleanup

[1] https://docs.openstack.org/releasenotes/tempest/v27.0.0.html#release-notes-27-0-0

Change-Id: I7ee881e8031a2198f3b307667bfd3e676459758d
diff --git a/neutron_tempest_plugin/fwaas/scenario/fwaas_v2_manager.py b/neutron_tempest_plugin/fwaas/scenario/fwaas_v2_manager.py
index ebd1584..517c96e 100644
--- a/neutron_tempest_plugin/fwaas/scenario/fwaas_v2_manager.py
+++ b/neutron_tempest_plugin/fwaas/scenario/fwaas_v2_manager.py
@@ -14,13 +14,11 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import netaddr
 from oslo_log import log
 
 from tempest import config
 from tempest.lib.common.utils import data_utils
 from tempest.lib.common.utils import test_utils
-from tempest.lib import exceptions as lib_exc
 from tempest.scenario import manager
 
 CONF = config.CONF
@@ -43,22 +41,6 @@
         if msg:
             raise cls.skipException(msg)
 
-    @classmethod
-    def setup_clients(cls):
-        super(ScenarioTest, cls).setup_clients()
-        # Clients (in alphabetical order)
-        cls.keypairs_client = cls.os_primary.keypairs_client
-        cls.servers_client = cls.os_primary.servers_client
-        # Neutron network client
-        cls.networks_client = cls.os_primary.networks_client
-        cls.ports_client = cls.os_primary.ports_client
-        cls.routers_client = cls.os_primary.routers_client
-        cls.subnets_client = cls.os_primary.subnets_client
-        cls.floating_ips_client = cls.os_primary.floating_ips_client
-        cls.security_groups_client = cls.os_primary.security_groups_client
-        cls.security_group_rules_client = (
-            cls.os_primary.security_group_rules_client)
-
 
 class NetworkScenarioTest(ScenarioTest):
     """Base class for network scenario tests.
@@ -80,72 +62,6 @@
         if not CONF.service_available.neutron:
             raise cls.skipException('Neutron not available')
 
-    def _create_subnet(self, network, subnets_client=None,
-                       routers_client=None, namestart='subnet-smoke',
-                       **kwargs):
-        """Create a subnet for the given network
-
-        within the cidr block configured for tenant networks.
-        """
-        if not subnets_client:
-            subnets_client = self.subnets_client
-        if not routers_client:
-            routers_client = self.routers_client
-
-        def cidr_in_use(cidr, tenant_id):
-            """Check cidr existence
-
-            :returns: True if subnet with cidr already exist in tenant
-                  False else
-            """
-            cidr_in_use = self.os_admin.subnets_client.list_subnets(
-                tenant_id=tenant_id, cidr=cidr)['subnets']
-            return len(cidr_in_use) != 0
-
-        ip_version = kwargs.pop('ip_version', 4)
-
-        if ip_version == 6:
-            tenant_cidr = netaddr.IPNetwork(
-                CONF.network.project_network_v6_cidr)
-            num_bits = CONF.network.project_network_v6_mask_bits
-        else:
-            tenant_cidr = netaddr.IPNetwork(CONF.network.project_network_cidr)
-            num_bits = CONF.network.project_network_mask_bits
-
-        result = None
-        str_cidr = None
-        # Repeatedly attempt subnet creation with sequential cidr
-        # blocks until an unallocated block is found.
-        for subnet_cidr in tenant_cidr.subnet(num_bits):
-            str_cidr = str(subnet_cidr)
-            if cidr_in_use(str_cidr, tenant_id=network['tenant_id']):
-                continue
-
-            subnet = dict(
-                name=data_utils.rand_name(namestart),
-                network_id=network['id'],
-                tenant_id=network['tenant_id'],
-                cidr=str_cidr,
-                ip_version=ip_version,
-                **kwargs
-            )
-            try:
-                result = subnets_client.create_subnet(**subnet)
-                break
-            except lib_exc.Conflict as e:
-                is_overlapping_cidr = 'overlaps with another subnet' in str(e)
-                if not is_overlapping_cidr:
-                    raise
-        self.assertIsNotNone(result, 'Unable to allocate tenant network')
-
-        subnet = result['subnet']
-        self.assertEqual(subnet['cidr'], str_cidr)
-
-        self.addCleanup(test_utils.call_and_ignore_notfound_exc,
-                        subnets_client.delete_subnet, subnet['id'])
-
-        return subnet
-
     def _create_router(self, client=None, tenant_id=None,
                        namestart='router-smoke'):
         if not client:
diff --git a/neutron_tempest_plugin/fwaas/scenario/test_fwaas_v2.py b/neutron_tempest_plugin/fwaas/scenario/test_fwaas_v2.py
index 3689bbf..4d5fdac 100644
--- a/neutron_tempest_plugin/fwaas/scenario/test_fwaas_v2.py
+++ b/neutron_tempest_plugin/fwaas/scenario/test_fwaas_v2.py
@@ -132,7 +132,7 @@
     def _create_network_subnet(self):
         network = self.create_network()
         subnet_kwargs = dict(network=network)
-        subnet = self._create_subnet(**subnet_kwargs)
+        subnet = self.create_subnet(**subnet_kwargs)
         return network, subnet
 
     def _create_test_server(self, network, security_group):