Move rebuild notification tests into separate method

The current rebuild testing in test_instance_action changes the image
used by the instance, therefore the actions tested in
test_instance_action had to be in specific order as testing rebuild
also changes the output json.

The rebuild test was moved from test_instance_action to its own method,
and now all the actions in test_instance_actions keeps the instance in
the same state.

Change-Id: Id0a7aaf8575d69deb89d3842b54fc23ee05b2153
Implements: bp versioned-notification-transformation-pike

doc/notification_samples/instance-reboot-error.json

@@ -2,7 +2,7 @@
     "event_type":"instance.reboot.error",
     "payload":{
         "nova_object.data":{
-            "architecture": null,
+            "architecture": "x86_64",
             "availability_zone": "nova",
             "created_at":"2012-10-29T13:42:11Z",
             "deleted_at":null,
@@ -38,7 +38,7 @@
             "auto_disk_config":"MANUAL",
             "kernel_id":"",
             "launched_at":"2012-10-29T13:42:11Z",
-            "image_uuid": "a2459075-d96c-40d5-893e-577ff92e721c",
+            "image_uuid": "155d900f-4e14-4e4c-a73d-069cbf4541e6",
             "metadata":{},
             "locked":false,
             "node":"fake-mini",