The TestPerformer for running tests on a data matrix did not allow to
throw any exceptions during its execution, thus requiring all exceptions
to be handled internally. This unnecessarily complicated exception
handling in tests.

This change allows TestPerformer implementation to throw exceptions that
may then directly be passed out of the test method. The test classes
with TestPerformer implementations are cleaned up by removing
unnecessary try-catch blocks or by replacing them with assertThrows
statements.