Add two more tests which check workflow execution

- added test that check execution of mixed workflow (Mistral v1)
- added test that check execution of direct workflow where all keywords are used
(on-error, on-success, on-finish)

Implements blueprint: mistral-workflow-execution-tests

Change-Id: I3055d0084a8f8a69bd8ac5cd51e7c5e7ce049b63
Merge "Add two more tests which check workflow execution"