This commit updates the image used in the subunit2sql-graph docs for
the run_time command. There was a fix pushed to set a floor value of
0 for the std_dev backfill since the docs were first added. This
updates the graph to use one that has this fix applied. This however
comes with the tradeoff of showing the few weeks were the infra
subunit2sql gearman worker was down and no data was collected.
Change-Id: I797db1d8a245cd6a89155ff716e09c61275aa2cf
0fe961094c