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.)

browser +
            " | rendering of page " +
            (page + 1) +
            " != reference rendering"
        );
        testUtils.ensureDirSync(testSnapshotDir);
        fs.writeFileSync(
          path.join(testSnapshotDir, page + 1 + ".png"),
          testSnapshot
        );
        fs.writeFileSync(
          path.join(testSnapshotDir, page + 1 + "_ref.png"),
          refSnapshot
        );
        
        const viewportString = `(${pageResult.viewportWidth}x${pageResult.viewportHeight}x${pageResult.outputScale})`;
        fs.appendFileSync(
          eqLog,
          "REFTEST TEST-UNEXPECTED-FAIL | " +
            browser +
            "-" +
            taskId +
            "-page" +
            (page + 1) +
            " | image comparison (==)\n" +
            `REFTEST   IMAGE 1 (TEST)${viewportString}: ` +
            path.join(testSnapshotDir, page + 1 + ".png") +
            "\n" +
            `REFTEST   IMAGE 2 (REFERENCE)${viewportString}: ` +
            path.join(testSnapshotDir, page + 1 + "_ref.png") +