playbooks: use group name variables consistently

[stuartgrace-bbc]

In many places, playbooks allow host group names such as 'mons' to be overriden by defining a variable such as 'mon_group_name'. This is very useful when ceph-ansible is sharing the ansible inventory with other playbooks and other hosts which expect different group names. But this was unfinished, with the variables used in some places but hard-coded names used in others places, sometimes within the same playbook.

This commit uses the group name variables everywhere so they can be reliably used to overrride the host group names.

Signed-off-by: Stuart Grace stuart.grace@bbc.co.uk

[gael-api]

I have a PR with the same goal. (But with unknown commits attached to it)
Some group_names are also present in prometheus jinja file :

• https://github.com/ceph/ceph-ansible/blob/main/roles/ceph-prometheus/templates/alertmanager.yml.j2
• https://github.com/ceph/ceph-ansible/blob/main/roles/ceph-prometheus/templates/prometheus.yml.j2

I think an all_group_name that replace all generic group must be implemented when inventory used is larger than the simple cluster inventory (as in a cloud dynamic inventory).