ActivityScenario changes behavior of Navigation Component and breaks backstack

### Description
When using `ActivityScenario`, backstack doesn't work as expected when launching deeplinks.

### Steps to Reproduce
Please see the repro project at https://github.com/lwasyl/activity-scenario-navigation-issue.
1. Navigation library is set up with navigation graph that defines deeplinks
2. Press the button to display a notification. The notification opens the app on FragmentB, with fragmentA in the backstack.
3. Press back button

### Expected Results
Fragment A is visible, as it's the previous one on the backstack.

### Actual Results
When starting main activity normally (via launcher), backstack works as expected: after clicking the notification, fragment B is visible. Then, after pressing back button, fragment A is visible.

When starting main activity via `ActivityScenario`, backstack doesn't work as expected: after clicking the notification, fragment B is visible, however after pressing back button, _app exits_.

Please note that the behavior was correct (that is, consistent with how the app behaves outside the tests) with `ActivityTestRule`, which is now deprecated. There's no clear migration path to test the now-failing case with `ActivityScenario`.

### AndroidX Test and Android OS Versions
`androidx.test.ext:junit-ktx:1.1.2`
Checked on various emulators and it doesn't seem to be related to OS version. Reproduced on API 26, 29, 30 (https://github.com/lwasyl/activity-scenario-navigation-issue/actions/runs/295793564)

### Link to a public git repo demonstrating the problem:
https://github.com/lwasyl/activity-scenario-navigation-issue

Here's how the app behaves normally:

When pressing back, app properly cycles through the backstack.

Here's UI tests that uses `ActivityScenario` and performs exactly the same steps as I did manually in the gif above (run the main activity, press button, press on notification, press back button):

fragmentA is never shown again

Beginne mit dem verlinkten Repro-Projekt und seinem UI-Test mit ActivityScenario; vergleiche anschließend dessen Lifecycle- und Backstack-Verhalten mit dem normalen Launcher-Flow und der veralteten ActivityTestRule. Reproduziere den Notification-Deeplink auf den aufgeführten API-Levels und ermittle, warum das Drücken von Zurück beendet, statt FragmentA anzuzeigen; fertig ist es, wenn der Test-Flow dem normalen App-Verhalten entspricht.

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