[Bug] pac admin create-service-principal assumes default environment admin

### Is there an existing issue?

- [x] I have searched the existing issues

### Description

Errors like the one included below can occur when the user following the app registration setup instructions do not have user admin permissions on the default environment. There is a workaround, which is to run 'pac auth' against an environment that is _not_ the default environment, but as the instructions stand, this is a real hurdle for users trying to set up the accelerator.

`Error: Principal user (Id=<>, type=8, roleCount=<>, privilegeCount=<>, accessMode='', AADObjectId='', MetadataCachePrivilegesCount=, businessUnitId=<>), is missing prvCreateUser privilege (Id=<>) on OTC=8 for entity 'systemuser' (LocalizedName='User'). context.Caller=<>. Consider adding missed privilege to one of the principal (user/team) roles.`

### Steps to Reproduce

```markdown

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### Expected Behavior

Run pac admin create-service-principal without errors.

### Anything else?

_No response_

Start by locating the accelerator's app registration setup instructions and the invocation of `pac admin create-service-principal`. Reproduce the failure when authenticated to the default environment, then verify that the command succeeds or that the documented setup avoids assuming default-environment admin permissions.

Written by the indexing model from the issue text.