[Catalyst] Update PreferenceLifecycleContext.notifyPreferenceChange

Change the signature from metadata to preference key, so that the API
could be used to notify other preferences on the same screen.

NO_IFTTT=Catalyst only

Bug: 332201912
Flag: com.android.settings.flags.catalyst
Test: atest
Change-Id: Ibdf5f9004471d5491a0be1e84365cbe9f136c373

src/com/android/settings/datausage/DataSaverScreen.kt

@@ -71,7 +71,7 @@ class DataSaverScreen :
     override fun hasCompleteHierarchy() = false
 
     override fun onStart(context: PreferenceLifecycleContext) {
-        val listener = DataSaverBackend.Listener { context.notifyPreferenceChange(this) }
+        val listener = DataSaverBackend.Listener { context.notifyPreferenceChange(KEY) }
         dataSaverBackendListener = listener
         dataSaverBackend = DataSaverBackend(context).apply { addListener(listener) }
     }