Fix WPT import by overriding product name to servo (#30457)

Upstream wpt script has bug where 'product' defaults to
'firefox' and this causes import of uninstalled python
modules specific to firefox runners.

Fixes #30452

Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>

python/wpt/update.py

@@ -103,8 +103,8 @@ def update_tests(**kwargs) -> int:
         if key not in args or args[key] is None:
             args[key] = value
 
-    set_if_none(kwargs, "product", "servo")
     set_if_none(kwargs, "config", os.path.join(WPT_PATH, "config.ini"))
+    kwargs["product"] = "servo"
     kwargs["store_state"] = False
 
     wptcommandline.set_from_config(kwargs)