Rename ansible groups to use _ instead of - (#7552)

* rename ansible groups to use _ instead of -

k8s-cluster -> k8s_cluster
k8s-node -> k8s_node
calico-rr -> calico_rr
no-floating -> no_floating

Note: kube-node,k8s-cluster groups in upgrade CI
      need clean-up after v2.16 is tagged

* ensure old groups are mapped to the new ones

roles/kubernetes/tokens/tasks/gen_tokens.yml

@@ -27,7 +27,7 @@
     TOKEN_DIR: "{{ kube_token_dir }}"
   with_nested:
     - [ 'system:kubelet' ]
-    - "{{ groups['kube-node'] }}"
+    - "{{ groups['kube_node'] }}"
   register: gentoken_node
   changed_when: "'Added' in gentoken_node.stdout"
   run_once: yes