Failed running devcontainer with container registry secret volume mounted

[toshikish]

In the case of running envbuilder in Kubernetes with container registry credential mounted (as mentioned in README.md), running fails with the following error:

error: remove docker config: remove /.envbuilder/config.json: device or resource busy

A potential cause is that envbuilder tries to delete the volume mounted credential file.

https://github.com/coder/envbuilder/blob/main/envbuilder.go#L771