Function under_pre_resolved_timeout 

pub(crate) async fn under_pre_resolved_timeout<F, T, E>(
    timeout: Duration,
    metrics: &ServerMetrics,
    fut: F,
) -> Result<T, E>
where
    F: Future<Output = Result<T, E>>,
    E: From<Error>,

Runs the pre-resolved phase under PRE_RESOLVED_TIMEOUT, counting an overrun.

fut must cover TLS negotiation, startup, authentication, and backend resolution. Proxying must run after it completes, outside the deadline. A zero timeout leaves fut unbounded.