https://chromium-review.googlesource.com/982601 disabled TBR for CLs that
modified OWNERS files. This CL relaxes the restriction to permit TBR for
CLs that have LGTMs for their modifications to OWNERS files.

Bug: 688115
Change-Id: I47fef6b1eb021ca7cdfc003dc57722643b174a6e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1797605
Commit-Queue: Alan Cutter <alancutter@chromium.org>
Auto-Submit: Alan Cutter <alancutter@chromium.org>
Reviewed-by: Aaron Gable <agable@chromium.org>