Tags from ignored posts (via preprocessor) still appear in collections props list (though empty)

[glyn]

I noticed that a tag from a draft post appeared in my production website, which was not what I expected to happen.

This occurs with eleventy base blog at the latest commit at the time of writing: 11ty/eleventy-base-blog@2e07e7c.

Steps to reproduce

1. Clone the repo https://codeberg.org/glyn/test-draft-tag-publication.
2. Change directory to the cloned repo.
3. Issue npm install.
4. Issue npx @11ty/eleventy.
5. Observe _site/tags/thistagshouldnotappear/.