Override the Copybara requirement if Bot-Commit+1

Automated rolls into Pigweed are usually tool-related, but in google3
we don't use those tools, so we don't need Copybara-Verified votes for
tool rolls. Also, the roller service account does not have permission
to trigger copybara into google3.

Change-Id: I1eb53fef8ea1a9f5b86cca8cfcade4b590aae5f7
Reviewed-on: https://pigweed-review.googlesource.com/c/Pigweed-Base/+/360013
Reviewed-by: Aaron Green <aarongreen@google.com>