Bext e2e: launch puppeteer with headless: false
Created by: lguychard
headless:false
was removed in https://github.com/sourcegraph/sourcegraph/commit/69fab829fb3efd6ccc0abac2466d80eb5c4e5219, but it appears to break e2e tests: https://buildkite.com/sourcegraph/sourcegraph/builds/38641#f60d5b4b-e544-4f46-89da-7fa16fcd4b41 (I also reproduced this locally).