Revert "Add an option --lab_preserve_logs to allow logs being saved before install."

refer to CL:
https://chromium-review.googlesource.com/#/c/209370/2

BUG=chromium:396177
TEST=None

Change-Id: I8fb6a6e5aa4853b3c774239af16c6ddddaf472cd
Reviewed-on: https://chromium-review.googlesource.com/209454
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
2 files changed