RFR: 8208693: HttpClient: Extend the request timeout's scope to cover the response body [v15]

[Daniel Fuchs]

On Tue, 11 Nov 2025 15:28:29 GMT, Volkan Yazici <vyazici at openjdk.org> wrote:

>> Currently `HttpRequest::timeout` only applies until the response headers are received. Extend its scope to also cover the consumption of the response body.
>> 
>> ### Review guidelines
>> 
>> 1. Read _"the fix"_ in `MultiExchange`
>> 2. Skim through the test server *handler* in `TimeoutResponseTestSupport`
>> 3. Review first `TimeoutResponseHeaderTest`, and then `TimeoutResponseBodyTest` (Mind the multiple `@test` blocks!)
>
> Volkan Yazici has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move `cancelTimerOnResponseBodySubscriberTermination` to `ExchangeImpl`

Marked as reviewed by dfuchs (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27469#pullrequestreview-3464166774