Set containerd version to 1.4.4 (#7398)

README.md

docs/containerd.md

docs/upgrades.md

docs/vars.md

inventory/sample/group_vars/all/containerd.yml

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

roles/container-engine/containerd-common/defaults/main.yml

...ontainer-engine/containerd-common/vars/debian-stretch.yml

roles/container-engine/containerd-common/vars/debian.yml

roles/container-engine/containerd-common/vars/fedora.yml

roles/container-engine/containerd-common/vars/redhat.yml

roles/container-engine/containerd-common/vars/ubuntu.yml

roles/container-engine/containerd/defaults/main.yml

roles/container-engine/containerd/templates/config.toml.j2

roles/kubernetes/preinstall/tasks/0020-verify-settings.yml

roles/kubespray-defaults/defaults/main.yaml

roles/kubespray-defaults/vars/main.yml

tests/common/_docker_hub_registry_mirror.yml

tests/files/packet_centos7-flannel-containerd-addons-ha.yml