Have the "update_depot_tools" script also do a CIPD tool sync. This will
ensure that users and systems have access to tooling at sync-time rather
than just-in-time loading them at execution time.

Update the tool boostraps to suppress any sort of syncing logs, if it
does happen. This will ensure that users who execute the tools don't see
unexpected output.

BUG=chromium:748651
TEST=local
  - Tested on Mac and Windows.

Change-Id: I1aad897d885a07beeac40a372a658681720efd2a
Reviewed-on: https://chromium-review.googlesource.com/591229
Commit-Queue: Daniel Jacques <dnj@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>