Firebase Auth Emulator interferes with Firebase Storage

### [READ] Step 1: Are you in the right place?

* For issues or feature requests related to __the code in this repository__
file a Github issue.
* If this is a __feature request__ make sure the issue title starts with "FR:".
* For general technical questions, post a question on [StackOverflow](http://stackoverflow.com/)
with the firebase tag.
* For general Firebase discussion, use the [firebase-talk](https://groups.google.com/forum/#!forum/firebase-talk)
google group.
* For help troubleshooting your application that does not fall under one
of the above categories, reach out to the personalized
[Firebase support channel](https://firebase.google.com/support/).

### [REQUIRED] Step 2: Describe your environment

* Operating System version: Windows 11
* Firebase SDK version: ____
* Library version: 9.1.1
* Firebase Product: auth, storage

### [REQUIRED] Step 3: Describe the problem

We access the Auth and Storage services in our project using this Java Admin SDK.
Recently, we wanted to make use of the Auth Emulator for development purposes. However, after enabling the emulator by setting the `FIREBASE_AUTH_EMULATOR_HOST` environment variable, the Storage calls stop working and return 401 Unauthorized.

It seems that by setting the `FIREBASE_AUTH_EMULATOR_HOST` environment variable, the [whole project enters an emulator mode](https://github.com/firebase/firebase-admin-java/blob/e8ec68c97929972acdbe05b79b5ea18f077a08a2/src/main/java/com/google/firebase/auth/internal/Utils.java#L27) and [uses emulator credentials](https://github.com/firebase/firebase-admin-java/blob/master/src/main/java/com/google/firebase/ImplFirebaseTrampolines.java#L47). The emulator credentials should be made to only apply to Auth calls.

Furthermore, I could not even find a way to create two instances of FirebaseApps (one with the emulator enabled and one disabled), since the check for `FIREBASE_AUTH_EMULATOR_HOST` is static and shared program-wide.

#### Steps to reproduce:

Use Auth and Storage in a production project. Enable `FIREBASE_AUTH_EMULATOR_HOST` and Storage stops working.

Beginne mit dem Lesen von src/main/java/com/google/firebase/auth/internal/Utils.java und src/main/java/com/google/firebase/ImplFirebaseTrampolines.java, insbesondere der Behandlung von FIREBASE_AUTH_EMULATOR_HOST und Emulator-Anmeldedaten. Reproduziere das Problem mit gleichzeitig aktiviertem Auth und Storage und überprüfe anschließend, dass Storage-Aufrufe weiterhin autorisiert bleiben, während Emulator-Anmeldedaten nur auf Auth angewendet werden; prüfe außerdem, ob sich separate FirebaseApp-Instanzen in ihrer Emulator-Konfiguration unterscheiden können.

Vom Indexierungsmodell aus dem Issue-Text verfasst.