ext/docker: test: remove misleading image names
ext/docker: test: remove misleading image names

- The image names are irrelevant to the test, only the
  result of the 'docker image' command is important.

samsalisbury/sous,opentable/sous,opentable/sous,opentable/sous,samsalisbury/sous,samsalisbury/sous,samsalisbury/sous,opentable/sous,samsalisbury/sous,opentable/sous