Web Feature query not finding tests included with `**`

[gsnedders]

See https://wpt.fyi/results/?label=master&label=experimental&aligned&view=interop&q=feature%3Acustomized-built-in-elements%20and%20path%3A%2Fcustom-elements%2Freactions%2Fcustomized-builtins

The relevant metadata file is: https://github.com/web-platform-tests/wpt/blob/c5aa7f3f769e443f25913b085089579f893cf07c/custom-elements/reactions/customized-builtins/WEB_FEATURES.yml

features:
- name: customized-built-in-elements
  files: "**"