[7.2.0] Angular HMR: FirebaseError: Firestore has already been started and persistence can no longer be enabled

### Version info

**Angular:** 13.2

**Firebase:** 9.6

**AngularFire:** 7.2

### How to reproduce these conditions

**Steps to set up and reproduce**

- serve Angular project with `ng serve --hmr`
- make some change in the application

### Debug output

** Errors in the JavaScript console **

`FirebaseError: Firestore has already been started and persistence can no longer be enabled. You can only enable persistence before calling any other methods on a Firestore object.`

### Expected behavior

No errors.

### Actual behavior

Project fails to run with the above error.

Might be related to #2655

使用 `ng serve --hmr` 提供 Angular 專案服務並修改應用程式，以重現此故障。接著追蹤 AngularFire 的 Firestore 初始化與持久化設定；當 HMR 變更不再產生 FirebaseError 時，issue 即完成。

由索引模型根據 Issue 內容生成。