Remove nova-network security groups methods

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

Replaced methods:
	* _create_security_group
	* _create_loginable_secgroup_rule

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: Idd6c9066cec143e358078babf1802dce60265114
diff --git a/manila_tempest_tests/tests/scenario/manager.py b/manila_tempest_tests/tests/scenario/manager.py
index d47d1b3..6cbaa8b 100644
--- a/manila_tempest_tests/tests/scenario/manager.py
+++ b/manila_tempest_tests/tests/scenario/manager.py
@@ -76,60 +76,6 @@
     # The create_[resource] functions only return body and discard the
     # resp part which is not used in scenario tests
 
-    def _create_loginable_secgroup_rule(self, secgroup_id=None):
-        _client = self.compute_security_groups_client
-        _client_rules = self.compute_security_group_rules_client
-        if secgroup_id is None:
-            sgs = _client.list_security_groups()['security_groups']
-            for sg in sgs:
-                if sg['name'] == 'default':
-                    secgroup_id = sg['id']
-
-        # These rules are intended to permit inbound ssh and icmp
-        # traffic from all sources, so no group_id is provided.
-        # Setting a group_id would only permit traffic from ports
-        # belonging to the same security group.
-        rulesets = [
-            {
-                # ssh
-                'ip_protocol': 'tcp',
-                'from_port': 22,
-                'to_port': 22,
-                'cidr': '0.0.0.0/0',
-            },
-            {
-                # ping
-                'ip_protocol': 'icmp',
-                'from_port': -1,
-                'to_port': -1,
-                'cidr': '0.0.0.0/0',
-            }
-        ]
-        rules = list()
-        for ruleset in rulesets:
-            sg_rule = _client_rules.create_security_group_rule(
-                parent_group_id=secgroup_id, **ruleset)['security_group_rule']
-            rules.append(sg_rule)
-        return rules
-
-    def _create_security_group(self):
-        # Create security group
-        sg_name = data_utils.rand_name(self.__class__.__name__)
-        sg_desc = sg_name + " description"
-        secgroup = self.compute_security_groups_client.create_security_group(
-            name=sg_name, description=sg_desc)['security_group']
-        self.assertEqual(secgroup['name'], sg_name)
-        self.assertEqual(secgroup['description'], sg_desc)
-        self.addCleanup(
-            test_utils.call_and_ignore_notfound_exc,
-            self.compute_security_groups_client.delete_security_group,
-            secgroup['id'])
-
-        # Add rules to the security group
-        self._create_loginable_secgroup_rule(secgroup['id'])
-
-        return secgroup
-
     def _image_create(self, name, fmt, path,
                       disk_format=None, properties=None):
         if properties is None: