Remove unused create_image of Nova v2 API

There are two create_image methods for Nova v2 API, but the one of
images_client.py only is used in most cases.
This patch removes the unused create_image of servers_client.py.

Change-Id: Icd457b6693c076c5c8b9d48bb88da162161c9a1a
Updated from global requirements

Change-Id: I3bc2ae9ccf8f5cb6f590dc51de389bfd7e920aa3
Merge "Updated from global requirements"
Merge "Remove unused create_image of Nova v2 API"
Merge branch 'master' of https://github.com/openstack/tempest