NCBC-559: During rebalance IConfigInfo impl is finalizing causing ODE

Change-Id: I7f4ef31bb8b9301f3d7e0c55b572d1e38b930b59
Reviewed-on: http://review.couchbase.org/39771
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Brett Lawson <brett19@gmail.com>