ansible.cfg: do not enforce PreferredAuthentications
ansible.cfg: do not enforce PreferredAuthentications

There's no need to enforce PreferredAuthentications by default.
Users can still choose to override the ansible.cfg with any additional
parameter like this one to fit their infrastructure.

Fixes: #4826

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

ceph/ceph-ansible,ceph/ceph-ansible