topology: call listpeerchannels_done directly

When cln is run without deprecated apis, the `listchannels` call would
still query `listpeerchannels`, even though it wouldn't use the result.
This adds unnecessary time to the call. Especially in case the node has
many channels. This commit skips the listpeerchannels call in case the
outcome won't be used.

Changelog-Fixed: Improve listchannels performance

Author: JssDWt

plugins/topology.c

@@ -381,7 +381,6 @@ static void gossmod_add_unknown_localchan(struct gossmap_localmods *mods,
 			      buf, chantok, gossmap);
 }
 
-/* FIXME: We don't need this listpeerchannels at all if not deprecated! */
 static struct command_result *listpeerchannels_done(struct command *cmd,
 					     const char *buf,
 					     const jsmntok_t *result,
@@ -472,9 +471,18 @@ static struct command_result *json_listchannels(struct command *cmd,
 				    "Can only specify one of "
 				    "`short_channel_id`, "
 				    "`source` or `destination`");
-	req = jsonrpc_request_start(cmd->plugin, cmd, "listpeerchannels",
+
+	// FIXME: Once this deprecation is removed, `listpeerchannels_done` can
+	// be embedded in the current function.
+	if (command_deprecated_out_ok(cmd, "include_private", "v24.02", "v24.08")) {
+		req = jsonrpc_request_start(cmd->plugin, cmd, "listpeerchannels",
 				    listpeerchannels_done, forward_error, opts);
-	return send_outreq(cmd->plugin, req);
+		return send_outreq(cmd->plugin, req);
+	}
+
+	// If deprecations are not necessary, call listpeerchannels_done directly,
+	// the output will not be used there.
+	return listpeerchannels_done(cmd, NULL, NULL, opts);
 }
 
 static void json_add_node(struct json_stream *js,