make ER only go back 10 days

Our Elastic Search index is down to 10 days, but ER looks at 14,
which makes people think bugs are showing up for the first time
10 days ago. Match the duration for ES.

Change-Id: I4e47ece38e68d4ee19ee61b9a107bba9f12abf8c
Merge "make ER only go back 10 days"