WebUI test: Fix automember tests according to new behavior
    
    After deleting user/host from group "rebuild" task is triggered,
    so the entity returns to the group. And we check if it exists.
    
    Also the order of cleaning test resources are changed:
    groups are being deleted only after corresponding rules.
    
    New automembership design description:
    https://www.port389.org/docs/389ds/design/automember-postop-modify-design.html
    
    Ticket: https://pagure.io/freeipa/issue/7881
    Reviewed-By: Armando Neto <abiagion@redhat.com>