Rotate recover_duts log files

This CL limits the number of log files to 10, 5M per file.

TEST=Ran the script locally, excersize the new function.
BUG=chromium:535621

Change-Id: Iefac314a1e5c571880421e8c6f03531c828f194e
Reviewed-on: https://chromium-review.googlesource.com/302193
Commit-Ready: Fang Deng <fdeng@chromium.org>
Tested-by: Fang Deng <fdeng@chromium.org>
Reviewed-by: Richard Barnette <jrbarnette@chromium.org>