purge-dashboard: check for legacy group name 'grafana-server'
purge-dashboard: check for legacy group name 'grafana-server'

When using the legacy group name 'grafana-server', this playbook will run but
won't remove properly all monitoring resources as expected.

Fixes: #7265

Signed-off-by: Guillaume Abrioux <30a9df5a0293a6108675377fa1673f7aa713f915@redhat.com>

ceph/ceph-ansible,ceph/ceph-ansible