Defaults: replace docker with containerd as our default container_manager (#8175)

* Defaults: replace docker with containerd as our default container_manager

* CI: Use docker for download_localhost test

* Defaults: with container_manager=containerd we need etcd_deployment_type=host

* CI: Run weave jobs with docker

* CI: Vagrant don't download_force_cache

* CI: Fix upgrade tests

* should run compatible with old settings, this means docker
* we need to run with a distro that has at least modern containerd,
  this means move from debian9 to debian10 to allow `containerd_version`
  to match between 2.17 and master

inventory/sample/group_vars/etcd.yml

@@ -19,4 +19,5 @@
 # etcd_peer_client_auth: true
 
 ## Settings for etcd deployment type
-etcd_deployment_type: docker
+# Set this to docker if you are using container_manager: docker
+etcd_deployment_type: host

inventory/sample/group_vars/k8s_cluster/k8s-cluster.yml

@@ -202,7 +202,8 @@ dns_domain: "{{ cluster_name }}"
 
 ## Container runtime
 ## docker for docker, crio for cri-o and containerd for containerd.
-container_manager: docker
+## Default: containerd
+container_manager: containerd
 
 # Additional container runtimes
 kata_containers_enabled: false