Fix nodepool integration tests

Failing on not having a statsd attribute.

Change-Id: If91428b33c73603993c1a4ff32eed60cdfe6d330
diff --git a/tests/nodepool/test_nodepool_integration.py b/tests/nodepool/test_nodepool_integration.py
index 9c87a10..bd22da3 100644
--- a/tests/nodepool/test_nodepool_integration.py
+++ b/tests/nodepool/test_nodepool_integration.py
@@ -30,6 +30,7 @@
     def setUp(self):
         super(TestNodepoolIntegration, self).setUp()
 
+        self.statsd = None
         self.zk = zuul.zk.ZooKeeper()
         self.addCleanup(self.zk.disconnect)
         self.zk.connect('localhost:2181')