Prior to this commit, the import was no longer relevant (since journal v0.0.31).
This commit fixes the import (and bumps the journal requirements).
It also:
- adapts journal_client instantiation with the missing brokers, group_id, etc... (as a plain import change was not enough).
- adds configuration checks on the journal client (+ tests)
This fixes the current ci build failure [1]
[1] https://jenkins.softwareheritage.org/job/DSEA/job/tests/260/console