Revert "Report a test priority to ResultsDB"
    
    This reverts commit 2bddabb7abdac4f6da4f24d836bd8d6b6b928b46.
    jskladan really didn't like the idea of storing priorities in
    ResultsDB even as a short-term measure, so we're taking a
    different approach.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>