Configure Sync Trigger based on number of vbuckets

Change-Id: Ib63ca2a55af52eb23aca2e3220d64ff8f5bec124
Reviewed-on: http://review.couchbase.org/43552
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Reviewed-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>
Tested-by: Deepkaran Salooja <deepkaran.couchbase@gmail.com>