MB-12144 compensate for possible one sample shift between bucket and
MB-12144 compensate for possible one sample shift between bucket and

...system stats. that doesn't completely guarantee that
/pools/default/buckets/default/stats returns exactly 60 samples when
asked for 60 samples, but at least removes constant fluctuation between
59 and 60 samples during the normal operation with the 1st minute of
stats archived

Change-Id: I9130fb6e4a5d0612f7a57fcf334a5c3643eeeabd
Reviewed-on: http://review.couchbase.org/51960
Tested-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>

nimishzynga/ns_server,membase/ns_server,mschoch/ns_server,nimishzynga/ns_server,membase/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,mschoch/ns_server,ceejatec/ns_server,ceejatec/ns_server,ceejatec/ns_server,nimishzynga/ns_server,membase/ns_server,membase/ns_server,mschoch/ns_server,mschoch/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,ceejatec/ns_server