Remove unnecessary warning logs from CouchNotifier.

Change-Id: I4450914ecdb27f1215c59d533541f3e22672b350
Reviewed-on: http://review.couchbase.org/34119
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>