Switch devtest images to only include o-c-c

Up until now we've been including heat-cfntools, which was somewhat
erroneously configuring cfn-hup to run os-refresh-config. The dependency
on os-refresh-config was in turn bringing in os-collect-config, which is
actually what the tripleo Heat templates expect now.

Change-Id: Ied4db80c4de9f3e7cbf629bec297766321053288