Any evocation of fireFunctions.httpsCallable make Angular Zone instable

### Version info

**Angular:**
12.1.1

**Firebase:**
9.1.3

**AngularFire:**
7.1.0

**Other (e.g. Ionic/Cordova, Node, browser, operating system):**
rxjs: 7.2.0

### How to reproduce these conditions

Any evocation of `fireFunctions.httpsCallable` make Angular Zone instable.

**Context**

In my angular application, I have a code that detects pending tasks executed inside Angular Zone. I noticed after upgrade on 7.1.0 that evocation of httpCallables leave long living tasks in the Zone. This was never an issue before. Even wrapping those calls into `ngZone.runOutsideAngular` doesn't help. Example:

```typescript
import {AngularFireFunctions} from '@angular/fire/compat/functions';
//...
constructor(private readonly fireFunctions: AngularFireFunctions) {
}

this.fireFunctions.httpsCallable('myFunc')(data); // this code creates a long living task inside zone and make it unstable

```

### Expected behavior

Evocation of httpCallable functions must not make zone unstable.

Reproduce el problema con Angular 12.1.1, Firebase 9.1.3, AngularFire 7.1.0 y RxJS 7.2.0 usando AngularFireFunctions de @angular/fire/compat/functions. Empieza en httpsCallable y comprueba cómo interactúa su invocación con Angular Zone, incluido cuando se envuelve en ngZone.runOutsideAngular. Se considera completado cuando las invocaciones de callables ya no dejan tareas pendientes de larga duración ni hacen que Zone sea inestable.

Escrito por el modelo de indexación a partir del texto del issue.