Issue 49850 -ldbm_get_nonleaf_ids() painfully slow for databases with many non-leaf entries
    
    Description:
    With a very large database, gathering non-leaf IDs for creating the ancestorid index took an enormous amount of time.
    This test is to verify the fix for this problem.
    
    https://pagure.io/389-ds-base/issue/49850
    
    Author: sgouvern
    
    Reviewed by: firstyear, spichugi