L3 - Default Context:
Currently camunda event correlation is done in the `CustomTracedCamundaEventFetcherService` that gets called from the mediator. This yields the chance of the import getting stuck if a whole page does not contain any activity events that could get correlated. As discussed we want to move the correlation past the mediator into the import service layer to avoid such situations completely.
AT:
- the `EventProcessInstanceImportMediator` calls a simple camundaActivity Event fetcher that returns full pages of camundaActivityevents
- there is a new import service facade for camunda activityEvents that performs the trace correlation by reading variables/businessKeys converts them to EventDto's and forwards the list of events to import to an instance of the generic EventProcessInstanceImportService