GitLab

1. Added --system-log-file argument to the runner script which saves
   Fuchsia debug logs in a file
2. Enabled that flag in run-swarmed.py.
3. Removed the LogReader.

Bug: 869753
Change-Id: I4ef5c375e06937533841bab2696d90ed49887a0f
Reviewed-on: https://chromium-review.googlesource.com/1162899
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581076}