vdk-structlog: add vdk_step_name and vdk_step_type to tests and fix filtering bugs

[DeltaMichael]

Overview

There are no tests that check if filtering vdk_step_name and vdk_step_type works correctly. This is not easy to do, because vdk_step_name and file_name often have the same value. We might have to change how the step name is displayed, so that it's not the same as the file name.

Filtering these two fields doesn't work correctly for json format. This is most likely due to the fact that we're adding the fields directly in the run_step hook, which executes after everything else has been filtered in the run_job hook.

Acceptance criteria

1. vdk_step_name and vdk_step_type added to functional tests for filtering
2. bugs with json formatting fixed