MB-10520 Fetch a deleted item for TAP BG fetch / backfill.

As the metadata fields for a deleted item should be replicated,
the deleted item should be fetched for TAP BG fetch or backfill.
Note that this is a regression from the recent change in the
master branch.

Change-Id: I24eae8e596ed70083875a948aec478f27bfbd68a
Reviewed-on: http://review.couchbase.org/34758
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: David Liao <david.liao@couchbase.com>