Add specific celery task arguments to metadata sent to systemd-journald
We used to log all task arguments, which was a bit too much for the logging pipeline to handle. Now that a lot of tasks arguments have been "canonicalized", we can go back to logging some specific arguments directly.
Use the opportunity to drop an unused argument and improve the documentation of these logging-related functions.
Related to swh-loader-core!160 (closed)
Test Plan
I'm not quite sure how to add tests to this stuff...
Migrated from D4043 (view on Phabricator)