* labs.wikimedia are the old old old labs/test projects, These are no
longer (and any that still wanted -> wmflabs)
* prototype.wikimedia are oldish test setups, and most should be moved
to wmflabs if still wanted
*.wmflabs.org are instances hosted on our Labs setup[1] which is our
virtuazlization cluster/project that Ryan setup, Which houses more
than just test wikis (Think Toolserver, but yes, with test wikis as
well).
[1].
https://www.mediawiki.org/wiki/Wikimedia_Labs