BUG/MINOR: h3: fix crash on h3s alloc failure

Do not emit a CONNECTION_CLOSE on h3s allocation failure. Indeed, this
causes a crash as the calling function qcs_new() will also try to emit a
CONNECTION_CLOSE which triggers a BUG_ON() on qcc_emit_cc().

This was reproduced using -dMfail.

This should be backported up to 2.7.
diff --git a/src/h3.c b/src/h3.c
index 909942b..09099ec 100644
--- a/src/h3.c
+++ b/src/h3.c
@@ -1707,7 +1707,6 @@
 	h3s = pool_alloc(pool_head_h3s);
 	if (!h3s) {
 		TRACE_ERROR("h3s allocation failure", H3_EV_H3S_NEW, qcs->qcc->conn, qcs);
-		qcc_emit_cc_app(qcs->qcc, H3_INTERNAL_ERROR, 1);
 		goto err;
 	}