Completely stop the Private Notifcation Service
When the app is closed (destroyed), it currently calls stop on the notification service's observer:
https://gitlab.torproject.org/tpo/applications/fenix/-/blob/tor-browser-82.0.0b4-10.0-1/app/src/main/java/org/mozilla/fenix/HomeActivity.kt#L364
```
override fun onDestroy() {
super.onDestroy()
// Diagnostic breadcrumb for "Display already aquired" crash:
// https://github.com/mozilla-mobile/android-components/issues/7960
breadcrumb(
message = "onDestroy()",
data = mapOf(
"finishing" to isFinishing.toString()
)
)
privateNotificationObserver?.stop()
```
Unfortunately, that doesn't stop the underlying Service:
https://gitlab.torproject.org/tpo/applications/android-components/-/blob/android-components-60.0.3-10.0-1/components/feature/privatemode/src/main/java/mozilla/components/feature/privatemode/notification/PrivateNotificationFeature.kt#L50
```
override fun stop() {
scope?.cancel()
}
```
This causes issues like the one described n https://gitlab.torproject.org/tpo/applications/fenix/-/merge_requests/49#note_2712256
issue