Add hanging test filter for timeout integration testing

[auni53]

Pending #4456, there's a TODO for testing request timeout with a test filter that hangs. This would test the request timeout path in the filter chain.

(to-be-outdated link)

[repokitteh-read-only]

talnordan is not allowed to assign users.

🐱

Caused by: a #4988 (comment) was created by @talnordan.

see: more, trace.

[talnordan]

If you'd like, I can help with this one.

[mattklein123]

@talnordan go for it. I sent you org invite so things can be assigned to you.

[auni53]

I don't really want to do this! But I'd be happy to help or advise, feel free to contact me :)

(I might be more responsive in email than slack, auni@google.com)