FIX Replication status attributes for schema backend not read from disk
https://github.com/OpenIdentityPlatform/OpenDJ/issues/140

Add ds-sync-* attributes from schema ldif to extraAttributes

Those attributes are used at startup to control which state the DS
presents to the RS,
and as a result which changes will be provided by the RS and applied by
the DS.

By reading the saved state and presenting it to the RS we only fetch and
replay newer
changes we don't already have and avoid fetching and trying to
re-playing the entire history.