This is a reland of commit 10dbd7ba

Original change's description:
> Remove old DepotToolsOwners implementation
>
> code-owners should have been enabled for most hosts that depot_tools
> supports by now. Remove our own implementation and rely on code-owners.
>
> Change-Id: Iaf0d3db65b2e5063b67d42b92188c4ec51d2cd9a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3783475
> Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>
> Reviewed-by: Joanna Wang <jojwang@chromium.org>
> Commit-Queue: Gavin Mak <gavinmak@google.com>

Change-Id: Ic87f34411bb38b91fcf49adb07601ae10244e828
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3881043Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Joanna Wang <jojwang@chromium.org>