Rename "VolumesCloneTest" class name to "VolumesV2CloneTest"

This class tests api version 2, so the class name should indicate this.

Change-Id: I704a67f528232a22ed7daad0666ca8a739aba400
diff --git a/tempest/api/volume/test_volumes_clone.py b/tempest/api/volume/test_volumes_clone.py
index 7529dc2..d8bd840 100644
--- a/tempest/api/volume/test_volumes_clone.py
+++ b/tempest/api/volume/test_volumes_clone.py
@@ -21,11 +21,11 @@
 CONF = config.CONF
 
 
-class VolumesCloneTest(base.BaseVolumeTest):
+class VolumesV2CloneTest(base.BaseVolumeTest):
 
     @classmethod
     def skip_checks(cls):
-        super(VolumesCloneTest, cls).skip_checks()
+        super(VolumesV2CloneTest, cls).skip_checks()
         if not CONF.volume_feature_enabled.clone:
             raise cls.skipException("Cinder volume clones are disabled")
 
@@ -46,5 +46,5 @@
         self.assertEqual(int(volume['size']), src_size + 1)
 
 
-class VolumesV1CloneTest(VolumesCloneTest):
+class VolumesV1CloneTest(VolumesV2CloneTest):
     _api_version = 1