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/6dcca481-5345-4466-ada3-2d068aea346b), [Sponge](http://sponge2/6dcca481-5345-4466-ada3-2d068aea346b) status: failed