Decrease squids cache max freshness time

Set the maximum time an object can be considered fresh to 1 day, 3 days
was a too aggressive considering a new package can be released, uploaded
to the openstack pypi mirror and set as a minimum requirement for a project in a shorter timeframe.

Closes-Bug: #1371549
Change-Id: If35d58de6a62bfc7ddd94d807c91c22fc8a09dda