test_planner: Stop writing the old oneof-style "test_unit" field

The recipe code has already been migrated to the new way.
e.g. no references to "test_unit" here: https://cs.corp.google.com/search/?q=package:%5E(chromeos).*$+f:%5Einfra/recipes+test_unit

BUG=chromium:963016
TEST=unit tests

Change-Id: Id31a919c64516ad1660e0e0c249db9eec60c1d6a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/test_planner/+/1613772
Reviewed-by: Sean Abraham <seanabraham@chromium.org>
Commit-Queue: Sean Abraham <seanabraham@chromium.org>
Tested-by: Sean Abraham <seanabraham@chromium.org>
5 files changed
tree: d235a9adc90c0c6bc75c6952dfdd5266aad5eb67
  1. .gitignore
  2. OWNERS
  3. cipd.yaml
  4. deploy_cipd.json
  5. deploy_cipd.sh
  6. src/