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: b94b4f225fc56e58fc0477d275172222e3c4e05b buildURL: [Build Status](https://source.cloud.google.com/results/invocations/025b0b7a-2ded-45f1-b366-42e092f52e00), [Sponge](http://sponge2/025b0b7a-2ded-45f1-b366-42e092f52e00) status: failed