Disable the sourceforge lister origins
This is a temporary workaround the time we make a first pass on those repositories.
This will allow to list sourceforge without immediately triggering the scheduling of those origins (as we cannot ensure we would respect the limit of 8 tasks in // otherwise).
Related to swh/infra/sysadm-environment#3350 (closed)
Migrated from D5803 (view on Phabricator)