Use the heat-container-agent from a system container.
It means that the docker daemon can be started later.
Pass as a software deployment with the heat-agent the following
software-configurations:
* prometheus-monitoring
** pin prometheus to v1.8.2 since its config is not 2.0.0
compatible
Add heat-container-agent container image.
Implements: blueprint heat-agent
Related-Bug: #1680900
Change-Id: I084b7fe51eddb7b36c74f9fe76cda37e8b48f646