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

contrib/dind/run-test-distros.sh

@@ -46,7 +46,7 @@ test_distro() {
     pass_or_fail "$prefix: netcheck" || return 1
 }
 
-NODES=($(egrep ^kube-node hosts))
+NODES=($(egrep ^kube_node hosts))
 NETCHECKER_HOST=localhost
 
 : ${OUTPUT_DIR:=./out}