The "initial" bootstrap exit 0 with a warning instead of a raw failure instead of failure if realm already exists

### Is your feature request related to a problem? Please describe.

I wanted to script a job in k8s to set up the "admin" realm and credientials and not have to do it manually. However, since it exits 0 on and upgrade, it fails the upgrade...

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Additional context

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Start by tracing the "initial" bootstrap path and its handling when the admin realm already exists; reproduce the behavior from the Kubernetes setup job described in the issue. Done means an existing realm produces a failure and non-zero exit instead of only a warning with exit 0, while the initial setup behavior remains usable.

Written by the indexing model from the issue text.