Firebase Auth Emulator interferes with Firebase Storage

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### [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.

先阅读 src/main/java/com/google/firebase/auth/internal/Utils.java 和 src/main/java/com/google/firebase/ImplFirebaseTrampolines.java，尤其关注 FIREBASE_AUTH_EMULATOR_HOST 和模拟器凭据的处理。启用 Auth 和 Storage 后一起复现该问题，然后验证 Storage 调用仍保持授权状态，而模拟器凭据仅应用于 Auth；同时检查不同的 FirebaseApp 实例是否可以使用不同的模拟器配置。

由索引模型根据 Issue 内容生成。