[fenix] Closes https://github.com/mozilla-mobile/fenix/issues/20127: fix app_received_intent extras.

Apparently, it had been using the wrong mapping this whole time. I can't
wrap my head around fenix's glean wrapper so I'm not sure if this
resulted in bugs or if my change changes the behavior. However, I don't
think anyone is using this probe so I'm requesting to remove it. If we
don't end up removing it, then we can check for bugs/changes in
behavior. This isn't ideal but I'd rather not spend the time on it if we
don't have to.

app/src/main/java/org/mozilla/fenix/components/metrics/Event.kt

@@ -403,8 +403,8 @@ sealed class Event {
 
         enum class Source { APP_ICON, LINK, CUSTOM_TAB, UNKNOWN }
 
-        override val extras: Map<Events.appOpenedAllStartupKeys, String>?
-            get() = hashMapOf(Events.appOpenedAllStartupKeys.source to source.name)
+        override val extras: Map<Events.appReceivedIntentKeys, String>?
+            get() = hashMapOf(Events.appReceivedIntentKeys.source to source.name)
     }
 
     data class CollectionSaveButtonPressed(val fromScreen: String) : Event() {