DCP consistency checker should work for the synchronous worker

The DCP client was rewritten to allow streaming 'n' vBuckets at a time; this was a requirement for backing up directly to the cloud. At the time we didn't introduce the consistency checker for the synchronous DCP worker because were under the impression that we would have DCP snapshotting (meaning the backup would always be consistent). This is no longer the case, so we need to reintroduce the consistency checker for the synchronous worker.