Context:
In the course of OPT-4564 it was found that the "Data Upgrade Test" stage of our branch builds is not running the data upgrade tests anymore but exits right after engine data generation since this change https://github.com/camunda/camunda-optimize/commit/f92798259e9e7f2f6a7cf512bbf00c91902222eb#diff-dfca6dc369fa94ee0231b727a52639143326926ec6f028078e1c3ca407e361a7R34 .

AT:

• fix the cause that prevents the "Data Upgrade Test" from running properly
• ensure this can never happen again without notice, the stage should fail if test results are not available when it finishes (e.g. using post actions)