Assume there is no decision change when test started
    
    This fixes some duplicate decision change messages if there are multiple
    resultsdb-consumers and RUNNING happened just before PASSED. In such
    case consumer that received RUNNING would publish decision change
    incorrectly if the PASSED test result is already in ResultsDB.
    
    This also helps lower the traffic a lot (ResultsDB, Koji, dist-git
    requests) because the resultsdb-consumers can ignore more than half of
    the ResultsDB messages.
    
    NOTE: The last decision change message may be inconsistent with the
    current decision in case there was an ERROR and the test is being rerun
    (QUEUED, RUNNING). The last decision change would mention failed result
    but current decision (from API) would mention missing result.
    
    JIRA: RHELWF-2053
    
    Signed-off-by: Lukas Holecek <hluk@email.cz>