infra: Add $build/siso properties to builders This is a preparation for Siso migration, and shouldn't change the behaviors of the bots, yet. Bug: b/401959048 Change-Id: I7c81e4bee5389214bb537ccb7efe08721f4ff7ff Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6339328 Auto-Submit: Junji Watanabe <jwata@google.com> Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Roman Lavrov <romanl@google.com> Reviewed-by: Roman Lavrov <romanl@google.com>