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 代码片段重现问题，并结合其他 provider 函数跟踪 provideRemoteConfig 入口点。验证 callback 为什么既不记录日志也不应用 minimumFetchIntervalMillis，然后确认 callback 会运行，并且开发环境的 fetch 间隔已应用。

由索引模型根据 Issue 内容生成。