pytest: fix test_xpay_fake_channeld flake

Also, resulting log was huge, so suppress log level (will probably speed test)

```
2025-09-02T06:01:39.4881086Z >       l1.rpc.plugin_start(os.path.join(os.getcwd(), 'plugins/cln-askrene'))
2025-09-02T06:01:39.4881090Z 
2025-09-02T06:01:39.4881174Z tests/test_xpay.py:279: 
...
2025-09-02T06:01:39.4883193Z >           self.sock.connect(str(self.path))
2025-09-02T06:01:39.4883340Z E           ConnectionRefusedError: [Errno 111] Connection refused
...
2025-09-02T06:01:41.7767610Z lightningd-1 2025-09-02T06:01:27.235Z **BROKEN** plugin-cln-xpay: askrene-age failed with {"code":-4, "message":"Plugin terminated before replying to RPC call."}
2025-09-02T06:01:41.7768127Z lightningd-1 2025-09-02T06:01:27.305Z INFO    plugin-cln-xpay: Killing plugin: exited during normal operation
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Author: rustyrussell

plugins/xpay/xpay.c

@@ -38,6 +38,8 @@ struct xpay {
 	bool take_over_pay;
 	/* Are we to wait for all parts to complete before returning? */
 	bool slow_mode;
+	/* Suppress calls to askrene-age */
+	bool dev_no_age;
 };
 
 static struct xpay *xpay_of(struct plugin *plugin)
@@ -2098,6 +2100,10 @@ static struct command_result *age_layer(struct command *timer_cmd, void *unused)
 
 static void start_aging_timer(struct plugin *plugin)
 {
+	struct xpay *xpay = xpay_of(plugin);
+
+	if (xpay->dev_no_age)
+		return;
 	notleak(global_timer(plugin, time_from_sec(60), age_layer, NULL));
 }
 
@@ -2422,6 +2428,7 @@ int main(int argc, char *argv[])
 	xpay = tal(NULL, struct xpay);
 	xpay->take_over_pay = false;
 	xpay->slow_mode = false;
+	xpay->dev_no_age = false;
 	plugin_main(argv, init, take(xpay),
 		    PLUGIN_RESTARTABLE, true, NULL,
 		    commands, ARRAY_SIZE(commands),
@@ -2434,5 +2441,8 @@ int main(int argc, char *argv[])
 		    plugin_option_dynamic("xpay-slow-mode", "bool",
 					  "Wait until all parts have completed before returning success or failure",
 					  bool_option, bool_jsonfmt, &xpay->slow_mode),
+		    plugin_option_dev("dev-xpay-no-age", "flag",
+				      "Don't call askrene-age",
+				      flag_option, flag_jsonfmt, &xpay->dev_no_age),
 		    NULL);
 }

tests/test_xpay.py

@@ -227,14 +227,21 @@ def test_xpay_fake_channeld(node_factory, bitcoind, chainparams, slow_mode):
 
     # l2 will warn l1 about its invalid gossip: ignore.
     # We throttle l1's gossip to avoid massive log spam.
+    # Suppress debug and below because logs are huge
     l1, l2 = node_factory.line_graph(2,
                                      # This is in sats, so 1000x amount we send.
                                      fundamount=AMOUNT,
                                      opts=[{'gossip_store_file': outfile.name,
                                             'subdaemon': 'channeld:../tests/plugins/channeld_fakenet',
                                             'allow_warning': True,
-                                            'dev-throttle-gossip': None},
-                                           {'allow_bad_gossip': True}])
+                                            'dev-throttle-gossip': None,
+                                            'log-level': 'info',
+                                            # xpay gets upset if it's aging when we remove cln-askrene!
+                                            'dev-xpay-no-age': None,
+                                            },
+                                           {'allow_bad_gossip': True,
+                                            'log-level': 'info',
+                                            }])
 
     # l1 needs to know l2's shaseed for the channel so it can make revocations
     hsmfile = os.path.join(l2.daemon.lightning_dir, TEST_NETWORK, "hsm_secret")