Improve unit test robustness

Summary: When running tests locally, some are quite flaky, and there is a lot of error logging noise. This diff doesn't remove all of it, but does reduce it significantly.

Reviewed By: nikoant

Differential Revision: D20034619

fbshipit-source-id: 183f74475b644f803b2f92b1b1301f4d0f6e193a

scripts/yarn-install.js

@@ -12,6 +12,7 @@ const util = require('util');
 const glob = util.promisify(require('glob'));
 const exec = util.promisify(require('child_process').exec);
 const PACKAGES = [
+  'headless-tests',
   'static',
   'src/plugins/*',
   'src/fb/plugins/*',