Improve tests coverage by adding missing model types in journal_data
Improve the coverage of the test set provided in journal_data, namely add directories, snapshots and skipped contents.
This requires to adapt a bit the function assert_all_objects_consumed() from pytest_plugin, because we want to be able to handle anonymizable objects specifically. So for now, simply add an 'exclude' argument.
Migrated from D3207 (view on Phabricator)