rspec: Websockets Sample responds to chat failed

Note: #1567 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky. ---- commit: 8e648735a4482472acd7cceada21c4f73d783e86 buildURL: [Build Status](https://source.cloud.google.com/results/invocations/fbc0eff5-0223-407b-93bd-37095673c5db), [Sponge](http://sponge2/fbc0eff5-0223-407b-93bd-37095673c5db) status: failed