[bbagent] retry UpdateBuild to set status=STARTED when get NotFound response
[bbagent] retry UpdateBuild to set status=STARTED when get NotFound response

Bug: b/216810142
Change-Id: I03dc6c2a708c7d8b422dd04829320eef5a0bcfbf
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/3425549
Reviewed-by: Scott Lee <1dcb292530f82960316cb3d87cd67c3f212b79cb@chromium.org>
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>

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