Fix CheckOwnersFormat so that it checks the new OWNERS files instead of the
original ones.

Change-Id: I4abb1cfc847bd28f45b9948fe7775c10dcc8a420
Reviewed-on: https://chromium-review.googlesource.com/c/1382946Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>