test_planner: Log build proto when it's missing a build target

The logging/error is already there, but it never happens because
getBuildTarget panics. https://screenshot.googleplex.com/Rmefn4EAJBD

Currently when build_target is missing from output properties, we just
get a panic stacktrace like this: https://screenshot.googleplex.com/Eef1dXHcy0D
There's already a place in the CreateTestPlan method that checks for
missing build targets, but it wasn't getting a chance to do its thing
because of this panicking. Now it will do said checking.

TEST=Unit tests

Change-Id: I345e0d5357f590c4deecabe71facda169f636e7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/test_planner/+/1609858
Tested-by: Sean Abraham <seanabraham@chromium.org>
Commit-Queue: Sean Abraham <seanabraham@chromium.org>
Reviewed-by: Evan Hernandez <evanhernandez@chromium.org>
Reviewed-by: David Burger <dburger@chromium.org>
3 files changed
tree: 961f8d34e6f2d93766ec47bbc19b8586bcb3553c
  1. .gitignore
  3. cipd.yaml
  4. deploy_cipd.json
  5. deploy_cipd.sh
  6. src/