selftest/dbcheck: Fix up RODC one-way links (use correct dbcheck rule)

selftest/dbcheck: Fix up RODC one-way links (use correct dbcheck rule)

The previous commit was correct on intention, but it was not noticed
as there is a race, that the incorrect rule was appended to.

These links are removed by remove_plausible_deleted_DN_links not
fix_all_old_dn_string_component_mismatch

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14642

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri Oct 15 10:00:47 UTC 2021 on sn-devel-184