remove Nova v3 XML testing

this removes the XML base clients, as well as skips any Nova v3
XML tests so that we can actually propose the patch to remove
v3 XML from Nova.

Part of bp:remove-v3-xml-api

Change-Id: I68ff62846346bac94a3b91366aa03f022f3f32b7
diff --git a/tempest/api/compute/base.py b/tempest/api/compute/base.py
index 872a841..9b9eb9f 100644
--- a/tempest/api/compute/base.py
+++ b/tempest/api/compute/base.py
@@ -261,6 +261,11 @@
     @classmethod
     def setUpClass(cls):
         # By default compute tests do not create network resources
+        if cls._interface == "xml":
+            skip_msg = ("XML interface is being removed from Nova v3. "
+                        "%s will be removed shortly" % cls.__name__)
+            raise cls.skipException(skip_msg)
+
         cls.set_network_resources()
         super(BaseV3ComputeTest, cls).setUpClass()
         if not cls.config.compute_feature_enabled.api_v3: