During FFU upgrades from 16.2 to 17.1 Ganesha upgrade don't find any host under ceph_nfs

Issue

• During FFU upgrades from 16.2 to 17.1, The documentation have a step to upgrade Ganesha.

ansible-playbook -i $HOME/overcloud-deploy/<stack>/tripleo-ansible-inventory.yaml \
    /usr/share/ansible/tripleo-playbooks/ceph-update-ganesha.yml \
     -e @$HOME/overcloud-deploy/<stack>/config-download/<stack>/global_vars.yaml \
     -e @$HOME/overcloud-deploy/<stack>/config-download/<stack>/cephadm/cephadm-extra-vars-heat.yml \
     -e @$HOME/ganesha_update_extravars.yaml

• However, this command failed due to the following error.

(undercloud) [stack@director ~]$ ansible-playbook -i /home/stack/overcloud-deploy/overcloud/tripleo-ansible-inventory.yaml  /usr/share/ansible/tripleo-playbooks/ceph-update-ganesha.yml -e @$HOME/overcloud-deploy/overcloud/config-download/overcloud/global_vars.yaml -e @$HOME/overcloud-deploy/overcloud/config-download/overcloud/cephadm/cephadm-extra-vars-heat.yml  -e @$HOME/ganesha_update_extravars.yaml
[WARNING]: Could not match supplied host pattern, ignoring: ceph_nfs

• The ansible playbook "/usr/share/ansible/tripleo-playbooks/ceph-update-ganesha.yml" refers to "ceph_nfs" group,

- hosts: ceph_nfs
  gather_facts: false
  tasks:

but the ansible inventory file /home/stack/overcloud-deploy//tripleo-ansible-inventory.yaml doesn't have such "ceph_nfs" group.