I've seen this test flake from time to time in CI. Here's a recent example: https://dev.azure.com/cncf/envoy/_build/results?buildId=161250&view=logs&jobId=767be981-567e-57d8-68c3-2140ede0a0bd&j=767be981-567e-57d8-68c3-2140ede0a0bd&t=2181edf2-f610-59f2-c43a-04bb9d0bca00 @abeyad @alyssawilk