Provide a “cluster monitor only” build of CMOS

The microlith is a great starting point, as it provides a full observability stack in a single docker image. However, many users will already have Prometheus/Alertmanager/Grafana and may simply be interested in the Cluster Monitor as a plug-in for these pipelines. While it is possible to disable all these components (and indeed will be the recommendation for the Developer Preview), this is a lot of wasted space.

Filing this task to track discussion around providing an alternative build containing just the Cluster Monitor. This will almost certainly be a Docker image (though we may wish to consider Deb/RPM deployments too). There is already a Dockerfile and Makefile for this in the repo, so this should not be difficult from a pure code perspective.