[resultdb] Log output
[resultdb] Log output

For debugging purposes, it is useful to see the actual rdb stdout.
Log it.

R=40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org

Bug: 1021849
Change-Id: If219ad30bac093b3d756cbc76100a79ba26e21b3
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/recipes-py/+/1972888
Commit-Queue: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Auto-Submit: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>

luci/recipes-py,luci/recipes-py