[buildbucket] bump up % of UpdateBuild by Go to 5
[buildbucket] bump up % of UpdateBuild by Go to 5

Bug: 1110990

Change-Id: I113de2a7772de07858766f32d8a4cd1997da5c09
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2688450
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Commit-Queue: Scott Lee <1dcb292530f82960316cb3d87cd67c3f212b79cb@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go