intg: Avoid using xrange in tests
    
    In Python 2 range() returns a list, and xrange() returns an object that
    will only generate the items in the range when needed, saving memory.
    
    In Python 3, the range() function is gone, and xrange() has been renamed
    range().
    
    We do not strictly require list or iterator in code therefore we can use
    range which is in poth version. And we do not use big ranges there
    so the memory overhead with list on python2 is not big.
    
    Reviewed-by: Martin Basti <mbasti@redhat.com>
    (cherry picked from commit 1fef02f87429597e82965a9870e4597e0fadf212)