MB-10382: Adapt UPR fake server accordingly

The keys of the return values of vbucket-seqno changed.

    vb_0_high_seqno -> vb_0:high_seqno
    vb_0_vb_uuid -> vb_0:vb_uuid

Change-Id: I95b2a54c45195232d4fde2acaf93b545fd6dc4ab
Reviewed-on: http://review.couchbase.org/34856
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: buildbot <build@couchbase.com>