Remove default.yaml from build output

[rkm]

In practice we've found this confusing as new developers should create their own config once for their local environment instead of editing the copy in the build output (which gets overwritten each time). The file is also deleted during deployments, so there doesn't seem to be much benefit in including it at all. Users can still copy the default file from the repo once when needed.

We may have to keep it in the test projects though for the CI runs.