Update storage for excluding apps from NAS features

Now that two adjustment keys have uis to opt out individual apps.
Also rename some variables/methods for clarity

Test: NotificationAssistantsTest
Test: NotificationManagerServiceTest
Bug: 377697241
Bug: 377697346
Bug: 390412878
Flag: android.app.nm_summarization
Change-Id: I1ad3dca2cd0c6149b7ea5c4a522e23e5c86a06c1