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

tests/files/packet_ubuntu18-flannel-ha.yml

@@ -0,0 +1,25 @@
+---
+# Instance settings
+cloud_image: ubuntu-1804
+mode: ha
+vm_memory: 1600Mi
+
+# Kubespray settings
+kubeadm_certificate_key: 3998c58db6497dd17d909394e62d515368c06ec617710d02edea31c06d741085
+kube_proxy_mode: iptables
+kube_network_plugin: flannel
+helm_enabled: true
+krew_enabled: true
+kubernetes_audit: true
+etcd_events_cluster_enabled: true
+local_volume_provisioner_enabled: true
+deploy_netchecker: true
+dns_min_replicas: 1
+kube_encrypt_secret_data: true
+ingress_nginx_enabled: true
+cert_manager_enabled: true
+# Disable as health checks are still unstable and slow to respond.
+metrics_server_enabled: false
+metrics_server_kubelet_insecure_tls: true
+kube_token_auth: true
+enable_nodelocaldns: false