* calico: add constant calico_min_version_required
and verify current deployed version against it.
* calico: remove upgrade support with data migration
The tool was used pre v3.0.0 and is no longer needed.
* calico: remove old version support from tasks
* calico: remove old ver support from policy ctrl
* calico: remove old ver support from node
* canal: remove old ver support
* remove unused calicoctl download checksums
calico_min_version_required is the oldest version that can be installed
Older versions can be removed.
Hans Feldt