mercurial.loader: Migrate away from SWHConfig mixin
Related to swh-core#1532 (closed) swh-core#1410 swh-core!159 (closed)
Test Plan
tox
and docker:
time doco exec swh-loader swh loader run mercurial https://forge.extranet.logilab.fr/open-source/pybill INFO:swh.loader.mercurial.Bundle20Loader:Load origin 'https://forge.extranet.logilab.fr/open-source/pybill' with type 'hg'
{'status': 'eventful'}
docker-compose exec swh-loader swh loader run mercurial 0.50s user 0.44s system 4% cpu 19.792 total
Migrated from D4127 (view on Phabricator)