Whether dynamically created entries in the ospfNbrTable
should be kept when the adjacency goes down.
If this object is set to 'false', then a dynamically created
entry in the ospfNbrTable will remain with state 'down' when
the adjacency is lost. Such entries can be deleted manually
by setting ospfNbrStatus to 'destroy'.
If this object is set to 'true', then dynamically created
entries in the ospfNbrTable will be deleted automatically
when the adjacency goes down.