Skip rescue tests for cells v1

The rescue tests in Tempest don't work with cells v1 so
let's skip them.

Change-Id: I234f778c9d264ee2e5fe6050ca6b33283be464f7
diff --git a/lib/tempest b/lib/tempest
index d8790f8..67b631e 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -398,6 +398,8 @@
         iniset $TEMPEST_CONFIG compute-feature-enabled shelve False
         # Cells doesn't support hot-plugging virtual interfaces.
         iniset $TEMPEST_CONFIG compute-feature-enabled interface_attach False
+        # Cells v1 doesn't support the rescue/unrescue tests in Tempest
+        iniset $TEMPEST_CONFIG compute-feature-enabled rescue False
 
         if  [[ -z "$DEFAULT_INSTANCE_TYPE" ]]; then
             # Cells supports resize but does not currently work with devstack