Deprecation notices has a slight rough edge

Question

### What version of Codex is running?

main

### What subscription do you have?

All of them

### Which model were you using?

any

### What platform is your computer?

Darwin 25.1.0 arm64 arm

### What issue are you seeing?

@jif-oai - your commit for #5825 works great, except for when there's not a 'new' feature flag:

```
⚠ `experimental_sandbox_command_assessment` is deprecated. Use `experimental_sandbox_command_assessment` instead.
```

### What steps can reproduce the bug?

Use the exper