test: add an extra case for obsolescence distributed case This changeset introduces a new documented test case for a distributed obsolescence scenario. The scenario involves a simple case where some obsolescence markers are retrieved before the changeset they affect. See the test case documentation for details. We also test variants where the changesets are added from a bundle.

test: add a test file dedicated to an important distributed case This test file introduces documented test case for obsolescence markers usage that are important to distributed workflow cases. In the distributed case, new changesets, markers, and phases can be added in orders that would not happen during the local only usage. Documenting these scenarios and test them is important as we make progress with various obsolescence aspects.