MB-7797: Lower bgfetch sleep time for 60s to 1s

Change-Id: I767599bb3d64c085ad406ee75d5d88ebb48effc3
Reviewed-on: http://review.couchbase.org/24842
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>