Add list_volumes scenario for Cinder test

Current Rally provides "create_and_list_volume" scenario, but doesn't
provide "list_volumes". User can specify number of volumes which will
be created in context.

Change-Id: I700282388b839d735448850e0629a0a37ab781f1

rally-jobs/rally-neutron.yaml

@@ -600,6 +600,25 @@
         failure_rate:
           max: 0
 
+  CinderVolumes.list_volumes:
+    -
+      args:
+        detailed: True
+      runner:
+        type: "constant"
+        times: 3
+        concurrency: 3
+      context:
+        users:
+          tenants: 2
+          users_per_tenant: 1
+        volumes:
+          size: 1
+          volumes_per_tenant: 2
+      sla:
+        failure_rate:
+          max: 0
+
   CinderVolumes.create_volume:
     -
       args:

tests/unit/fakes.py

@@ -221,7 +221,9 @@ class FakeSample(FakeResource):
 
 
 class FakeVolume(FakeResource):
-    pass
+    @property
+    def _info(self):
+        return {"id": "uuid"}
 
 
 class FakeVolumeType(FakeResource):