Hi Christopher Zell,
the reason I wanted you to align the test case was that you should use the upgrade test rule instead of queries by process definition key. In the migration test suite there can be multiple instances of a process definition so such queries are not the best approach.
If you instead use the upgrade test rule queries, which use an unique business key, these problems do not exist.
I adjusted the test case, see: https://github.com/camunda/camunda-bpm-platform/commit/f4bb3768535315e6d5957e8471e6155fc7bc78ea