Fix DefaultSubnetPool API test

As default subnetpool is a unique resource in the cloud, it needs to be
cleaned after each test is done. This patch adds a cleanup call to
DefaultSubnetPool tests in order to delete created default subnet pool.

Change-Id: I4c963d0d0e9910f7047061b51feb36c8a19de65c
Closes-bug: #1709938
diff --git a/neutron/tests/tempest/api/test_subnetpools.py b/neutron/tests/tempest/api/test_subnetpools.py
index a2d4fe8..e2fb3d6 100644
--- a/neutron/tests/tempest/api/test_subnetpools.py
+++ b/neutron/tests/tempest/api/test_subnetpools.py
@@ -336,6 +336,10 @@
 
 class DefaultSubnetPoolsTest(SubnetPoolsTestBase):
 
+    def setUp(self):
+        self.addCleanup(self.resource_cleanup)
+        super(DefaultSubnetPoolsTest, self).setUp()
+
     @classmethod
     def resource_setup(cls):
         super(DefaultSubnetPoolsTest, cls).resource_setup()