Puppetize the PowerDNS database passwords

When we rotated database credentials, the service broke because the password for the database user powerdns@localhost is not managed by Puppet on the MySQL/MariaDB side.

In passing, the MySQL root password in the secondary DNS stored in /root/.my.cnf is also not Puppetized and the run of Puppet Agent breaks after that password is changed in the MariaDB server of the primary DNS server.