In preparation for retiring a number of mailing lists from
lists.openstack.org which have had no activity for over three years,
remove their configuration so our deployment automation won't
recreate them once they're gone. Also remove references to the
third-part-announce list in our documentation, since that's one of
the unused lists we're removing. See the announcement at
http://lists.openstack.org/pipermail/openstack-discuss/2022-February/027404.html
for details.
Change-Id: Ieedd8613363039d19d3ae47f1a83a38747419bdc
1f1443a2c8