zoom into avg_bg_wait_time as well
zoom into avg_bg_wait_time as well

Change-Id: I5673c416d14eed1cc33adc6c825973c46742e109
Reviewed-on: http://review.couchbase.org/30530
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

couchbase/cbmonitor,couchbase/cbmonitor