Remove authentication requirement from firebase functions:shell when using a demo project

### [REQUIRED] Environment info

**firebase-tools:** 10.0.1

**Platform:** Windows

### [REQUIRED] Test case

Try to connect to a demo project using `firebase functions:shell` when not logged in to Firebase's CLI

### [REQUIRED] Steps to reproduce

1) Log out of Firebase CLI

```
firebase logout
```

2) Start Firebase Emulator with a demo project. Demo projects are described here: https://firebase.google.com/docs/emulator-suite/connect_auth#choose_a_firebase_project

```
firebase emulators:start --project demo-project
```

3) Start functions:shell and point to demo project

```
firebase functions:shell --project demo-project
```

This results in this error:

```
Error: Failed to authenticate, have you run firebase login?
```

### [REQUIRED] Expected behavior

Using `functions:shell` to connect to a demo project shall be allowed without having a Firebase account.

### [REQUIRED] Actual behavior

Can't access demo project through `functions:shell` unless I sign in to Firebase CLI