Not all sample images are built and tested in CI/PR validation

https://github.com/dotnet/dotnet-docker/pull/4534 restructured some of the sample dockerfiles, but left some of them, like [Dockerfile.debian](https://github.com/richlander/dotnet-docker/blob/654dbd52d157901292a22f20bf34006ff0a27bb6/samples/aspnetapp/Dockerfile.debian) unable to build and/or run.

The [dotnet-docker-samples](https://dev.azure.com/dnceng/internal/_build?definitionId=376) pipeline only ends up building images that we publish (defined in manifest.samples.json). There should be some additional PR validation that runs `pwsh .\build-and-test.ps1 -Path *samples* -TestCategories sample`.