Maven wrapper now found during K8s docker build

[ml170722d]

The image for k8s can not be build because the Maven wrapper is not found.

Build fails on this line. https://github.com/steve-community/steve/blob/6cdc22bfa056f5d21d6513db7104ce057607148a/k8s/docker/Dockerfile#L24

The issue is that the .mvn directory and mvnw executable are not added to the docker image during the build.