Remove ovn4nfv support (#8265)

.gitlab-ci/packet.yml

README.md

docs/_sidebar.md

docs/ansible.md

docs/ci.md

docs/ovn4nfv.md

roles/download/defaults/main.yml

roles/kubernetes-apps/network_plugin/meta/main.yml

roles/kubernetes-apps/network_plugin/ovn4nfv/tasks/main.yml

roles/kubernetes/node/templates/kubelet.env.v1beta1.j2

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

...s/kubernetes/preinstall/tasks/0050-create_directories.yml

roles/network_plugin/meta/main.yml

roles/network_plugin/ovn4nfv/defaults/main.yml

roles/network_plugin/ovn4nfv/tasks/main.yml

roles/network_plugin/ovn4nfv/templates/ovn-daemonset.yml.j2

...etwork_plugin/ovn4nfv/templates/ovn4nfv-k8s-plugin.yml.j2

tests/files/packet_ubuntu18-ovn4nfv.yml