project.config: accept LUCI-TryBot-Result in addition to TryBot-Result

The pre-submit testing as implemented in LUCI has reached a point where
a passing LUCI-TryBot-Result provides sufficient signal to consider the
the TryBots-Pass submit requirement met.

Change-Id: I319727b88314b8758afe32674fb5a16eaad3c5ab
Reviewed-on: https://go-review.googlesource.com/c/All-Projects/+/523735
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>