Unable to configure settings in provideRemoteConfig

### Version info

**Angular:**
^12.2.9

**Firebase:**
^9.1.2

**AngularFire:**
^7.1.0

**Other (e.g. Ionic/Cordova, Node, browser, operating system):**

"rxfire": "^6.0.2",
"rxjs": "^6.6.7",

Node LTS (14)
npm@6

### How to reproduce these conditions

**Failing test unit, Stackblitz demonstrating the problem**

**Steps to set up and reproduce**

Copy the following code in the `imports` modules of `AppModule`:

```ts
provideFirebaseApp(() => initializeApp(environment.firebase)),
provideAuth(() => getAuth()),
provideMessaging(() => getMessaging()),
provideAnalytics(() => getAnalytics()),
provideRemoteConfig(() => {
console.log('provideRemoteConfig')
const remoteConfig = getRemoteConfig();

if (isDevMode()) {
console.log('isDevMode')
remoteConfig.settings.minimumFetchIntervalMillis = 10 * 1000;
}

return remoteConfig;
}),
```

### Expected behavior

It should run the code (console.log, etc...) and set the fetch time in dev env.

### Actual behavior

Currently, it does nothing (no console output) and it's really hard to work with Remote Config since it's 12 hours throttle update with default settings...

使用 AppModule 程式碼片段重現問題，並與其他 provider 函式一同追蹤 provideRemoteConfig 進入點。驗證 callback 為什麼既不記錄日誌也不套用 minimumFetchIntervalMillis，然後確認 callback 會執行，且開發環境的 fetch 間隔已套用。

由索引模型根據 Issue 內容生成。