boolean cancelAllScheduledFutures() {
            if (pingFuture != null) {
                pingFuture.cancel(false);
            }
            return timeoutFuture.cancel(false);
        }
Extends the request timeout by the specified {@code longPollingTimeoutMillis}, because otherwise
the client will get {@code "503 Service Unavailable} due to a {@link RequestTimeoutException} before
long-polling finishes.
core/src/main/java/com/linecorp/armeria/server/healthcheck/HealthCheckService.java