restrict bonus configs to GCE *SAN bots

The config refactor inadvertently included Android and Mac *SAN bots.

Change-Id: I158c25be9fbd098cd903741eb78209c8ee95d8df
Reviewed-on: https://skia-review.googlesource.com/148302
Auto-Submit: Mike Klein <mtklein@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
2 files changed