Fixing test_backup_and_restore assert to do not rely on the order
    
    Since we cannot assume that LDAP will return data in any ordered way,
    the test should be changed to do not rely on that.
    
    Instead of just comparing the output of the show-user command, this change
    first order the groups returned in the 'Member of Group' field before
    compare them.
    
    https://pagure.io/freeipa/issue/7339
    
    Reviewed-By: Aleksei Slaikovskii <aslaikov@redhat.com>
    Reviewed-By: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>