Mark security group fullstack tests as stable

It has been some time since we marked the security group tests in
fullstack as unstable.  Now that mark is impeding the fullstack tests
for stateless security groups.

Based on testing it appears that the unstable tests are specific to the
linuxbridge driver, which is not really very much supported these days.
Testing for that driver is dropped, since it is better to at least test
for the other scenarios than nothing at all.

Change-Id: Ib1ef0763496aa536ba80f1c34c64d8a6c313fd0b
Needed-By: https://review.opendev.org/710252
Related-bug: #1779328

neutron/tests/fullstack/test_securitygroup.py

@@ -18,7 +18,6 @@ from oslo_utils import uuidutils
 
 from neutron.cmd.sanity import checks
 from neutron.common import utils as common_utils
-from neutron.tests import base as tests_base
 from neutron.tests.common import net_helpers
 from neutron.tests.fullstack import base
 from neutron.tests.fullstack.resources import environment
@@ -86,6 +85,7 @@ class TestSecurityGroupsSameNetwork(BaseSecurityGroupsSameNetworkTest):
 
     network_type = 'vxlan'
     scenarios = [
+        # TODO(njohnston): Re-add the linuxbridge scenario once it is # stable
         # The iptables_hybrid driver lacks isolation between agents and
         # because of that using only one host is enough
         ('ovs-hybrid', {
@@ -95,10 +95,6 @@ class TestSecurityGroupsSameNetwork(BaseSecurityGroupsSameNetworkTest):
         ('ovs-openflow', {
             'firewall_driver': 'openvswitch',
             'l2_agent_type': constants.AGENT_TYPE_OVS,
-            'num_hosts': 2}),
-        ('linuxbridge-iptables', {
-            'firewall_driver': 'iptables',
-            'l2_agent_type': constants.AGENT_TYPE_LINUXBRIDGE,
             'num_hosts': 2})]
 
     index_to_sg = [0, 0, 1, 2]
@@ -106,7 +102,6 @@ class TestSecurityGroupsSameNetwork(BaseSecurityGroupsSameNetworkTest):
     # NOTE(toshii): As a firewall_driver can interfere with others,
     # the recommended way to add test is to expand this method, not
     # adding another.
-    @tests_base.unstable_test("bug 1779328")
     def test_securitygroup(self):
         """Tests if a security group rules are working, by confirming
         that 0. traffic is allowed when port security is disabled,