Notification throttling: allow progress -> no progress update

In both client-side and server-side throttling. Basically, instead of just allowing completed progress, allow any transition between different values of no/partial/completed progress.

Bug: 425364383
Test: atest NotificationTest NotificationManagerTest NotificationManagerServiceTest
Flag: android.app.notification_update_shedding_allow_progress_completion
Change-Id: Idac6bce7a64bdeabcab20e1c39016d8b7f65b5c6