Run //test/... on Linux CI (bazelbuild#463)

Author: keith

.bazelci/presubmit.yml

@@ -26,7 +26,7 @@ x_defaults:
     test_targets:
       - "--"
       - "//examples/..."
-      # - "//test/..." TODO: Enable once https://github.com/bazelbuild/continuous-integration/pull/1015 is deployed
+      - "//test/..."
       - "-//examples/apple/..."
 
 tasks: