xenapi: Do not retry snapshot upload on 500

If Glance returns a 500 response on an initial attempt to upload
a snapshot image, it will set the image status to killed.  Any retry
attempts will fail with a 409 response.

Hence, Nova should not attempt to retry the upload in this case, which
will eliminate many pointless retries.

Closes-Bug: 1349933

Change-Id: I1a8f2416923a368b02cf8963c747ebbb24d749a1
Removes unnecessary instructions in test_hypervapi

Lines have no actual effect on the tests. Removing them
will facilitate further unit tests.

Partial-Bug: #1220256

Change-Id: I805aba5e75f2640221b2dc0034950c0832841247
Code change for nova support cinder client v2

Use v2 volume endpoint to attach/detach volume would be failed,
due to nova not supporting cinder client v2 yet. This patch is for
nova support cinder client v2.

Implements bp support-cinderclient-v2
Closes-Bug: #1215772
Co-Authored-By: Mike Perez <thingee@gmail.com>
Co-Authored-By: Yaguang Tang <yaguang.tang@canonical.com>

Change-Id: Id8abbbb4d9b0c8c49ab51fc3d958ef0d487467f8
Merge "xenapi: Do not retry snapshot upload on 500"
Merge "Removes unnecessary instructions in test_hypervapi"
Merge "Code change for nova support cinder client v2"