Improve logging for failed Chain Executions in the EventJobManager implementation

Currently the EventJobManager only provides detailed loggings if an chain execution does not finish before the configured timeout. However it does not log similar information if an execution fails.

This issue will provide logging including:

• the called EnhancementEngines and the Status of the execution (INFO level)
• the serialized ExecutionMetadata for detailed analysis (DEBUG level). "text/turtle" will be used if a serializer for this format is available (OPTIONAL dependency). If not the toString() method of Triples will be used.