Don't fail tests if no tests present

If the project has no tests, don't consider that a failure.  This
way we can run "bazelisk test plugins/foo/..." and it will succeed
if the plugin has no tests.

Bazelisk apparently return RC 4 in that case.

Change-Id: I274bdf78f5d9dc953aa335dc2d694e213a03a2aa
2 files changed
tree: f8d7d9897c87481822d94514ce6288270c2b7f1e
  1. .gitreview
  2. LICENSE
  3. README
  4. playbooks/
  5. roles/
  6. zuul.d/