Remove volumes-v2-copy-volume-to-image (no tests)

volumes-v2-copy-volume-to-image was included in an earlier change.
During the review [1] it was noted a couple of times that tests were
missing for this capability, but the patch still landed with
the capability included.  DefCore doesn't consider Capabilities that
have no tests [2] since that leaves us without a way for vendors to
demonstrate compliance with an established definition of "working", so
this needs to be removed.

[1] https://review.openstack.org/#/c/221631/
[2]
http://git.openstack.org/cgit/openstack/defcore/tree/doc/source/process/CoreDefinition.rst#n131

Change-Id: I943a74181d0aed2dc1f607ededa7df3d3d485c03

next.json

@@ -74,7 +74,6 @@
         "volumes-v2-list",
         "volumes-v2-update",
         "volumes-v2-copy-image-to-volume",
-        "volumes-v2-copy-volume-to-image",
         "volumes-v2-clone",
         "volumes-v2-qos",
         "volumes-v2-availability-zones",
@@ -2503,25 +2502,6 @@
         }
       }
     },
-    "volumes-v2-copy-volume-to-image": {
-      "achievements": [
-        "deployed",
-        "future",
-        "complete",
-        "stable",
-        "discover",
-        "doc",
-        "foundation",
-        "atomic",
-        "proximity"
-      ],
-      "admin": false,
-      "description": "Volume copy-to-image operations with the Cinder v2 API",
-      "project": "cinder",
-      "required-since": "",
-      "tests": {
-      }
-    },
     "volumes-v2-clone": {
       "achievements": [
         "deployed",