Feature 9912: Kubernetes VCA in K8s installation

Changes:
- bootstrap juju to k8s
- add lxd as external cloud
- iptables are not needed anymore
- expose the vca to the outside using metallb

Change-Id: I15b33cbf621af00c53c4f12836500aecafcfcb9a
Signed-off-by: David Garcia <david.garcia@canonical.com>