Fix "apply NAS adjustment" when a notification is enqueued multiple times

Because the Adjustment object is modified when applying it (for some keys), applying it to multiple NotificationRecords would not work correctly starting from the second enqueued copy. And because the last one wins, this effectively resulted in the adjustment not being applied at all.

Fixes: 429948005
Test: atest NotificationManagerServiceTest
Flag: EXEMPT simple bugfix
Change-Id: Ic111fa1d85e79e34cbe6f54dc3e0c2e08cdb1182