MINOR: mux-quic: use timeout server for backend conns

Use timeout server in qcc_init() as default timeout for backend
connections. No impact for the moment as QUIC backend support is not
implemented.
diff --git a/src/mux_quic.c b/src/mux_quic.c
index f4d200d..f24e6cb 100644
--- a/src/mux_quic.c
+++ b/src/mux_quic.c
@@ -1818,7 +1818,8 @@
 	qcc->proxy = prx;
 	/* haproxy timeouts */
 	qcc->task = NULL;
-	qcc->timeout = prx->timeout.client;
+	qcc->timeout = conn_is_back(qcc->conn) ? prx->timeout.server :
+	                                         prx->timeout.client;
 	if (tick_isset(qcc->timeout)) {
 		qcc->task = task_new_here();
 		if (!qcc->task)