Report test 'scenario' to ResultsDB
    
    Summary:
    See https://lists.fedoraproject.org/archives/list/resultsdb-users@lists.fedoraproject.org/message/DJSIOLA3YEH6HNSJEXVPLIZT5TW4CDED/
    for some discussion of this. To make life easier for consumers
    of our results from ResultsDB, we should report the 'scenario'
    of the test. This allows consumers to conveniently deduplicate
    results: results for the same 'item' and 'scenario' are dupes,
    so usually, consumers will only want to consider the most recent
    one.
    
    Test Plan:
    Check the tests pass, report some results to a test
    ResultsDB and check the scenario item in the extradata looks
    correct.
    
    Reviewers: jskladan, jsedlak
    
    Reviewed By: jsedlak
    
    Subscribers: kparal, tflink
    
    Differential Revision: https://phab.qa.fedoraproject.org/D1155