Make internal state marker variables upper-case
    
    We use variables to track test state across modules, sometimes.
    As this is all internal to the test logic I didn't bother always
    making these variables upper-case, but os-autoinst now treats
    lower-case variables as a fatal error, so we have to change.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>