ipatests: mark known failures for autoprivategroup
    
    Two tests have known issues in test_trust.py with sssd 2.8.2+:
    - TestNonPosixAutoPrivateGroup::test_idoverride_with_auto_private_group
    (when called with the "hybrid" parameter)
    - TestPosixAutoPrivateGroup::test_only_uid_number_auto_private_group_default
    (when called with the "true" parameter)
    
    Related: https://pagure.io/freeipa/issue/9295
    Signed-off-by: Florence Blanc-Renaud <flo@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>