Migrate computev2 API tests to resource_* fixtures

Partially-implements bp:resource-cleanup

Change-Id: I59eb2d9789368c812282ce12ae7e571be720badb
diff --git a/tempest/api/compute/servers/test_servers_negative.py b/tempest/api/compute/servers/test_servers_negative.py
index b9ec29e..b86ee06 100644
--- a/tempest/api/compute/servers/test_servers_negative.py
+++ b/tempest/api/compute/servers/test_servers_negative.py
@@ -42,8 +42,8 @@
         super(ServersNegativeTestJSON, self).tearDown()
 
     @classmethod
-    def setUpClass(cls):
-        super(ServersNegativeTestJSON, cls).setUpClass()
+    def resource_setup(cls):
+        super(ServersNegativeTestJSON, cls).resource_setup()
         cls.client = cls.servers_client
         if CONF.compute.allow_tenant_isolation:
             cls.alt_os = clients.Manager(cls.isolated_creds.get_alt_creds())