As can be seen from the first round of testing in PR #15864, trying to update Puppeteer beyond version `19.0.0` completely breaks testing in Firefox. Curiously it does work locally when the `--noChrome` flag is being used, so it seems to be an issue with running tests in both Chrome *and* Firefox in parallel.

We need to fix this, likely by making some adjustments to our test-suite, such that we don't get "stuck" on an older version of Puppeteer without being able to update. (A temporary work-around could also be to disable testing in Chrome.)

onAllSessionsClosed = onAllSessionsClosedAfterTests(name);
  startServer();
  server.hooks.POST.push(unitTestPostHandler);
  const startUrl = `http:${host}:${server.port}${testUrl}`;
  startBrowsers(function (session) {
    session.numRuns = 0;
    session.numErrors = 0;
  }, makeTestUrl(startUrl));
}
function startIntegrationTest() {
  onAllSessionsClosed = onAllSessionsClosedAfterTests("integration");
  startServer();
  const { runTests } = require("./integration-boot.js");
  startBrowsers(function (session) {
    session.numRuns = 0;
    session.numErrors = 0;
  });
  global.integrationBaseUrl = `http:${host}:${server.port}/build/generic/web/viewer.html`;
  global.integrationSessions = sessions;
  Promise.all(sessions.map(session => session.browserPromise)).then(
    async () => {
      const results = { runs: 0, failures: 0 };
      await runTests(results);
      sessions[0].numRuns = results.runs;
      sessions[0].numErrors = results.failures;
      await Promise.all(sessions.map(session => closeSession(session.name)));
    }
  );
}
function unitTestPostHandler(req, res) {