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: a743f4030b03b56d5872466b4a075c07db8090df buildURL: [Build Status](https://source.cloud.google.com/results/invocations/b60fed3a-cd0f-45b3-ac04-60e359d23fd7), [Sponge](http://sponge2/b60fed3a-cd0f-45b3-ac04-60e359d23fd7) status: failed