test_client: Fix failing test since recent swh-model update
swh.model.tests.swh_model_data.TEST_OBJECTS["revision"] now has three sample revisions resulting in two revisions being processed by kafka consumer in test_client_with_deserializer.
As there is no guarantee on the order messages are processed by kafka consumer, we need to update test implementation to avoid failures.
Migrated from D7422 (view on Phabricator)