[#68346578] Set TLD to `development` for Puppet

So that it matches the `govuk::host` entries in Puppet. This prevents the
machine's FQDN from changing on the first Puppet run, now that we purge
unmanaged `hosts(5)` entries (which gets rid of `127.0.1.1`).
Merge pull request #22 from alphagov/68346578-set_tld_for_fqdn

[#68346578] Set TLD to `development` for Puppet