This does not change the behavior, just makes it more explicit rather than
relying on the "presubmit" string being present in the builder name, which is
about to be deprecated.

R=machenbach@chromium.org, tandrii@chromium.org

No-Try: true
No-Tree-Checks: true
Bug: chromium:893955
Change-Id: I99724b42510a93012dd40e338b1ff8f4047c1276
Reviewed-on: https://chromium-review.googlesource.com/c/1280582Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56685}