This reverts commit 2cf835a9.

Reason for revert: doesn't work with depot_tools

error 404 Not found: tools (with applied patch from 2729404)

Bug: 1183975

Original change's description:
> presubmit: Skip owners checks if code-owners plugin is enabled.
>
> If code-owners plugin is enable for the repo, skip owners check on
> commit, and skip checking owners format, as that will be done by
> the plugin.
>
> Change-Id: I1663baef4f0f27b00423071343fe740f6da50ce7
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2727131
> Auto-Submit: Edward Lesmes <ehmaldonado@chromium.org>
> Reviewed-by: Gavin Mak <gavinmak@google.com>
> Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

Change-Id: Id4d560701e4b0144e0aafc5263e09ed6927f6222
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2729409
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>