Fix ubuntu16/centos8 CI jobs (#7972)

roles/container-engine/containerd-common/vars/ubuntu-16.yml

roles/container-engine/docker/vars/ubuntu-16.yml

tests/files/packet_centos8-kube-ovn.yml

tests/files/packet_ubuntu16-canal-kubeadm-ha.yml

tests/files/packet_ubuntu16-canal-sep.yml

tests/files/packet_ubuntu16-flannel-ha.yml

tests/files/packet_ubuntu16-kube-router-sep.yml

tests/files/packet_ubuntu16-kube-router-svc-proxy.yml

tests/files/packet_ubuntu16-weave-sep.yml