Remove use of 'cls.enabled = False'

Various network scenario tests have been setting this attribute
when raising skip exceptions.  It appears to no longer be used for
anything and can be removed.

Change-Id: I368f9e08cba6372010b9fed47f7730160e9d60b1

tempest/scenario/test_load_balancer_basic.py

@@ -48,12 +48,10 @@ class TestLoadBalancerBasic(manager.NetworkScenarioTest):
         cfg = config.network
         if not test.is_extension_enabled('lbaas', 'network'):
             msg = 'LBaaS Extension is not enabled'
-            cls.enabled = False
             raise cls.skipException(msg)
         if not (cfg.tenant_networks_reachable or cfg.public_network_id):
             msg = ('Either tenant_networks_reachable must be "true", or '
                    'public_network_id must be defined.')
-            cls.enabled = False
             raise cls.skipException(msg)
 
     @classmethod

tempest/scenario/test_network_advanced_server_ops.py

@@ -46,7 +46,6 @@ class TestNetworkAdvancedServerOps(manager.NetworkScenarioTest):
                 or CONF.network.public_network_id):
             msg = ('Either tenant_networks_reachable must be "true", or '
                    'public_network_id must be defined.')
-            cls.enabled = False
             raise cls.skipException(msg)
 
     @classmethod

tempest/scenario/test_network_basic_ops.py

@@ -83,7 +83,6 @@ class TestNetworkBasicOps(manager.NetworkScenarioTest):
                 or CONF.network.public_network_id):
             msg = ('Either tenant_networks_reachable must be "true", or '
                    'public_network_id must be defined.')
-            cls.enabled = False
             raise cls.skipException(msg)
 
     @classmethod

tempest/scenario/test_network_v6.py

@@ -42,14 +42,13 @@ class TestGettingAddress(manager.NetworkScenarioTest):
     def check_preconditions(cls):
         if not (CONF.network_feature_enabled.ipv6
                 and CONF.network_feature_enabled.ipv6_subnet_attributes):
-            cls.enabled = False
             raise cls.skipException('IPv6 or its attributes not supported')
         if not (CONF.network.tenant_networks_reachable
                 or CONF.network.public_network_id):
             msg = ('Either tenant_networks_reachable must be "true", or '
                    'public_network_id must be defined.')
-            cls.enabled = False
             raise cls.skipException(msg)
+
         super(TestGettingAddress, cls).check_preconditions()
 
     def setUp(self):

tempest/scenario/test_security_groups_basic_ops.py

@@ -116,14 +116,12 @@ class TestSecurityGroupsBasicOps(manager.NetworkScenarioTest):
     def check_preconditions(cls):
         if CONF.baremetal.driver_enabled:
             msg = ('Not currently supported by baremetal.')
-            cls.enabled = False
             raise cls.skipException(msg)
         super(TestSecurityGroupsBasicOps, cls).check_preconditions()
         if not (CONF.network.tenant_networks_reachable or
                 CONF.network.public_network_id):
             msg = ('Either tenant_networks_reachable must be "true", or '
                    'public_network_id must be defined.')
-            cls.enabled = False
             raise cls.skipException(msg)
 
     @classmethod