Adapt to g_string_free glib 2.75.3 change

glib 2.75.3 changes warning behaviour of `g_string_free()`.
See:
* https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3219
* https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3226

Use this opportunity to replace the use of GString with
`g_strdup_printf()` where possible.
Otherwise correctly take the return value of `g_string_free()`
which is nicer anyways.

src/ui/console.c

@@ -310,9 +310,7 @@ _room_triggers_to_string(GList* triggers)
         }
     }
 
-    char* result = triggers_str->str;
-    g_string_free(triggers_str, FALSE);
-    return result;
+    return g_string_free(triggers_str, FALSE);
 }
 
 void