Bug: Not all features from a collection are picked by the index

Today I noticed that there's only a single [devcontainers-extra feature](https://github.com/devcontainers-extra/features) listed on https://containers.dev/features page (which is odd because all of them were listed previously)

I decided to check if it's reflected in [ghcr.io/devcontainers/index](https://github.com/orgs/devcontainers/packages/container/package/index) container, and indeed I spotted that the latest image (`sha256:67c13a273e686aee435df0ae312d367608716ed1a1c30fdc34bf18203733ac83`) contains only one feature for devcontainer-extra entry:


While the previous image (`sha256:5bbca131daff58a0ad98af37d527a0bd7c0c4e0c99bca4e9cb0b78fa34e3aa7e`) contains the normal number of devcontainer-extra features:


The currently available feature is `ghcr.io/devcontainers-extra/features/homebrew-package`


On the [devcontainers-extra container registry](https://github.com/orgs/devcontainers-extra/packages?tab=packages&q=homebrew-package) I can see that that feature is kind of doubled:


That's probably something I messed up, and as the result it messed up the process that is producing the index image with `devcontainer-index.json` file (so it only contains that single feature for devcontainers-extra collection)

Nevertheless, I don't know how that build process works, so I cannot check what exactly causes the issue and try to fix it (it was also mentioned in #480)

My only assumption is that it may be fixed when I remove doubled homebrew-package feature. Although the 1st image is namespaced with `ghcr.io/devcontainers-extra`, while the second is namespaced with `ghcr.io/devcontainers-extra/features`, so it still could be something else

@bamurtaugh is it possible to get more information about the build process of ghcr.io/devcontainers/index image? It may help to clarify what causes the issue, and maybe with fixing it