It's running slowly for now as the current execution is simply a loop over the mapping
file then execute the ingestion. We could make it go faster leveraging the
loader_oneshot and rabbitmq.
For this, we need to iterate over the mapping file and send tasks `swh.loader.mercurial.tasks.LoadMercurial`
with the proper parameters.
And that should be enough as the loader_oneshot already consumes those tasks ^.
That will make the ingestion go faster since the loader_oneshot is currently configured with a concurrency of 7.