Context:
To ensure event process feature upgrade regression we have to extend the data migration tests to retrieve and interact with event process entities.

AT:

• the `org.camunda.optimize.test.data.upgrade.PostMigrationTest` tests perform regression checks on functionality related to these indices
  • evaluate a report on an published event based process and ensure there is instance data
  • republish an event based process and wait for it to publish successfully and ensure instance data is available