Dev container features seem to get reinstalled on a prebuild

I'm not sure when this started happened but I'm noticing that if I:
- Prebuild an image using the latest version of `devcontainer`
- Reference the output image in my Dockerfile
- Rebuild the container using the latest version of the dev containers extension

I'm seeing my features, which should already be installed at the given version, go through the install process again. The purpose of prebuilding images is to avoid this downtime, so the fact they are not being skipped seems to defeat the entire purpose of that step.

One of the `features` configs where I'm seeing this:

```
"features": {
"docker-from-docker": "latest",
"kubectl-helm-minikube": "latest",
"git": "system",
"git-lfs": "3.1.4",
"ghcr.io/devcontainers/features/github-cli:1": {}
},
```

`devcontainer` version: 0.26.1
Dev containers version: v0.266.1

Note that if I rebuild the image without cache, I'm not seeing this behavior. It loads very quickly. It only seems to be the first time I use a new image.

The build pipeline we are using:
- Build a base image using docker
- Build a prebuild using `devcontainer`
- Update dev container configs to point to the output from `devcontainer`

Prebuild

First time opening dev container