blackbox/dbcheck-links.sh: reproduce lost deleted object problem

blackbox/dbcheck-links.sh: reproduce lost deleted object problem

When a parent object is removed during the tombstone garbage collection
before a child object and samba-tool dbcheck runs at the same time, the
following can happen:

- If the object child had DISALLOW_MOVE_ON_DELETE in systemFlags,
  samba-tool dbcheck moves the object under the LostAndFound[Config]
  object (as an originating update!)
- The lastKnownParent attribute is removed (as an originating update!)

These originating updates cause the object to have an extended time
as tombstone. And these changes are replicated to other DCs,
which very likely already removed the object completely!

This means the destination DC of replication has no chance to handle
the object it gets from the source DC with just 2 attributes (name, lastKnownParent).

The destination logs something like:

  No objectClass found in replPropertyMetaData

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13816

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>