Consider 'in-use' a non-pending volume for caching

We don't cache volume list if one of the volumes is in pending state, as
otherwise we'd miss the cloud-side cache invalidation. However, active
volumes that are attached are in state "in-use" - so basically if you
had one active volume, the cache would never cache.

Change-Id: I03cbc1b814e4a5829936a22751ee81d52b83fb2e

releasenotes/notes/cache-in-use-volumes-c7fa8bb378106fe3.yaml

@@ -0,0 +1,4 @@
+---
+fixes:
+  - Fixed caching the volume list when volumes are in
+    use.

shade/openstackcloud.py

@@ -65,7 +65,7 @@ OBJECT_CONTAINER_ACLS = {
 def _no_pending_volumes(volumes):
     '''If there are any volumes not in a steady state, don't cache'''
     for volume in volumes:
-        if volume['status'] not in ('available', 'error'):
+        if volume['status'] not in ('available', 'error', 'in-use'):
             return False
     return True