Subsequent shells e.g. `kubectl/docker exec` don't enter as the expected user

I.e. using https://github.com/coder/envbuilder-starter-devcontainer, which sets up user `coder` when `docker exec` get:

`root@remote-development:/workspaces/envbuilder-starter-devcontainer#`

Can then `sudo -su coder` and the environment is as expected.

Reproduce the behavior with the envbuilder-starter-devcontainer example and a subsequent docker exec or kubectl exec shell. Investigate how the container user is selected, then verify that subsequent shells enter as coder rather than root and retain the expected environment.

Rédigé par le modèle d'indexation à partir du texte de l'issue.