Revert detailed reporting in ActivationProcessor

Commit 40db48a introduced more detailed
operation result reporting in ActivationProcessor (three results for
three independent parts). However, this broke handling custom exceptions
thrown from ProjectionMappingLoader#load. To resolve this quickly, the
new operation results were removed. In the future, we should perhaps
stop using ObjectNotFoundException in the loader instead.

Fixes failing tests. Related to MID-9154.