test: remote_tls bounds-connections test flakes under load #4038

//crates/tracedecay:unit_test daemon::http_application_tests::remote_tls::remote_tls_listener_bounds_connections_and_expires_incomplete_headers failed under host load in three consecutive merge gates on 2026-10-15 (#4003, #4024/#4030, #4036). It passed 3 of 3 alone each time.

Its sibling, remote_tls_listener_does_not_apply_ingress_timeout_to_a_slow_handler, failed because the test sent its request only after the TLS handshake returned. If the test thread stalled past the listener's 200 ms idle deadline, the listener closed the connection first. #4036 fixed that by sending the request with the handshake. This test likely has a similar assumption: a connection-bound count, or an incomplete-header expiry measured against a wall-clock window that a stalled test thread overruns.

Done when the cause is found under the contention recipe from #3976, or with a delay injected at the race point, and the test waits on the event it checks. Raising a timeout does not count.