Update references to istio-node DaemonSet (renamed to istio-cni-node)

In OSSM 2.2.0, the istio-node DaemonSet is renamed to istio-cni-node to match the name in upstream Istio. 

The name should be updated in the documentation and a note about the rename should be added to the release notes.

For example, the istio-node DaemonSet is mentioned here: https://docs.openshift.com/container-platform/4.10/service_mesh/v2x/removing-ossm.html

For OSSM 2.1.x and earlier
 
$ oc delete -n openshift-operators daemonset/istio-node

For OSSM 2.2.0
 
$ oc delete -n openshift-operators daemonset/istio-cni-node