dynamicproxy: Make no user agent 403 more verbose

Change-Id: Id0b61ab2b96d4eaf810b3116e91230cd3d80067e
dynamicproxy: Store only one day of nginx logs

tools-webproxy is running out of space!

Change-Id: Ie17d7954871e84f3084f9edbf7c2e41039debbea