Rewrite http gh16810 test to not be online

[bukka]

This changes the test to not access external resources but use php cli server

[cmb69]

I'm very much in favor of avoiding online test, so thank you!

However, we still have about 30 online tests (master branch), so it might make sense to actually run these in some of the nightly CI jobs (might be a bit flaky, but better than not noticing issues).

[bukka]

However, we still have about 30 online tests (master branch), so it might make sense to actually run these in some of the nightly CI jobs (might be a bit flaky, but better than not noticing issues).

We already discussed it in #8390 and I'm still not really in favour of this as they might be flaky and the flaky tests take time to check and are quite annoying. I have been trying to reduce the flakiness of the test suite in the last few months (e.g. the ephemeral port conversion) so I will try to put more effort into the online conversion. Think some of them are pretty easy to do.