[resultdb] Remove stale TODO
[resultdb] Remove stale TODO

It was done in https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1931291

R=332b6c56634d0f63001046c664a2370006a02420@chromium.org, jchinlee@chromium.org

Change-Id: I0328a7b6eeb1017c0f59425e98490fa32b65db52
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1932577
Auto-Submit: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Commit-Queue: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>
Reviewed-by: Chan Li <332b6c56634d0f63001046c664a2370006a02420@chromium.org>

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