plugin-barman-cloud chart doesn't allow user to specify server cert dnsNames or the pluginServerName annotation

In my environment I'm not allowed to have a cert dns name like `barman-cloud`. It must be `barman-cloud.svc`. This was addressed in https://github.com/cloudnative-pg/cloudnative-pg/pull/9222 by adding a new annotation in the barman-cloud service: `cnpg.io/pluginServerName`

The plugin-barman-cloud chart does not allow us to change the dnsNames or add the new annotation to the service. I tried using the Values.service.name but that gives an error that service name is not a valid DNS-1035 label.

Start by locating the plugin-barman-cloud chart's Service template and the existing Values.service configuration, then render the chart with representative values. Done means users can configure the certificate dnsNames and add the cnpg.io/pluginServerName annotation without triggering the service-name validation error.

Written by the indexing model from the issue text.