MB-7149: Consider DGM case when transferring data
MB-7149: Consider DGM case when transferring data

Under DGM scenario, ep_engine not only will transfer items in memory,
but also all items on disk.

Change-Id: Ia3fc1819e5b27318b392266d18fc2c4a9f1cf0bf

couchbaselabs/couchbase-cli,couchbaselabs/couchbase-cli,couchbase/couchbase-cli,couchbaselabs/couchbase-cli,couchbase/couchbase-cli