Add the dot suffix to configured servers when missing

[Felipe Reyes]

the configuration option nameserver expects each value (space delimited) has a dot (.) at the end, currently when this dot is missing the servers creation fails and this error doesn't bubble up, the neutron-api charm adds the dot automatically when it's missing in the dns-domain config option.

https://github.com/openstack/charm-neutron-api/blob/master/hooks/neutron_api_context.py#L165-L183

The designate charm should behave in the same way to help the operator get the system up-n-running in this case.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-designate/+/819695

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-designate/+/819695
Committed: https://opendev.org/openstack/charm-designate/commit/81c8cbf4a60de9dcc454cdc8717d67ad31f55ea2
Submitter: "Zuul (22348)"
Branch: master

commit 81c8cbf4a60de9dcc454cdc8717d67ad31f55ea2
Author: Felipe Reyes <email address hidden>
Date: Mon Nov 29 15:31:56 2021 -0300

    Add final dot when missing in nameservers

    The configuration option nameserver expects each value to have a dot (.)
    at the end, currently when this dot is missing the servers creation
    fail, the error doesn't bubble up. On the neutron-api charm adds the dot
    automatically when it's missing in the dns-domain config option, this
    change makes the Designate charm behave in the same way.

    Change-Id: If335c9b5b1b2adca3e39fa4f1d182dfbe362f874
    Closes-Bug: #1952656