TESTS: Order list of entries in some lists
    
    Some tests started to fail because we depended on specific
    order of users in groups or messages in ldb results to be
    returned and that order changed.
    
    This patch adds a simple helper functions into these tests
    that order the entries before comparison with expected results.
    more deterministic.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/3563
    
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>
    (cherry picked from commit caae0e53e6091806634943699f4398b6a20273b4)