azd pipeline config should fail when --no-prompt is set

## Description

`azd pipeline config` is a fully interactive command that relies on user prompts for critical decisions (selecting CI/CD provider, repository, authentication type, federated credential subjects, etc.). It is not designed for unattended/CI scenarios.

Currently, when `--no-prompt` is set, `azd pipeline config` silently uses default values for all prompts. This can lead to incorrect configurations without any user awareness — for example, creating federated credentials with the wrong OIDC subject format (see #7374 / #7705).

## Proposal

`azd pipeline config` should return an error when `--no-prompt` is set, with a clear message explaining that this command requires interactive input and does not support unattended execution.

```
Error: azd pipeline config requires interactive input and cannot be run with --no-prompt.
```

## Context

This was identified during review of #7705, where both @jongio and @wbreza noted that the silent fallback behavior in `--no-prompt` mode could silently create mismatched federated credentials — re-creating the exact class of bug that PR is fixing.

## Related

- #7374 — OIDC subject mismatch issue
- #7705 — Fix for OIDC custom subject claims