CBQE-0: make cache fetch retry info loglevel

Change-Id: Iee0dcad2d0f6ca88e7eb6bc1c164a86862e131c2
Reviewed-on: http://review.couchbase.org/25470
Reviewed-by: Tommie McAfee <tommie@couchbase.com>
Tested-by: Tommie McAfee <tommie@couchbase.com>