devserver: rotate devserver log twice a day.

This CL changes devserver log's rotation to twice a day.

BUG=chromium:656829
TEST=test it locally with setting rotation to every 30s, verify it
works.

Change-Id: Ie7843dcb2e7f4191eed24f3b62f9cde65d46dbf4
Reviewed-on: https://chromium-review.googlesource.com/435021
Commit-Ready: Xixuan Wu <xixuan@chromium.org>
Tested-by: Xixuan Wu <xixuan@chromium.org>
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
1 file changed