MB-12820: Set AccessScannerTask's runtime to 2AM GMT

This is to make it consistent with documentation.

Change-Id: Ib6e6c2aed5f7d1beb5cf52d370845330ac879074
Reviewed-on: http://review.couchbase.org/43978
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: abhinav dangeti <abhinav@couchbase.com>