data/defaults: Add new sub domains for staging infra

Defines a private staging.internal.swh.network dns subdomain.

The public facing part (.staging.softwareheritage.org) needs to be addressed outside of puppet within swh's gandhi account (done).

Related T1876

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Migrated from D1702 (view on Phabricator)

Adapt according to review

Update and branch to other branch

Some references in the commit message have been migrated:

• T1876 is now infra/sysadm-environment#1876

Plug diff to production branch

What does bind::zones do/mean?

Merge request was merged

closed