Update CoreSettingsObserver internal state correctly.

When a setting gets deleted, it needs to be removed from
CoreSettingsObserver internal state too.

Bug: 117555066
Test: atest services/tests/servicestests/src/com/android/server/am/CoreSettingsObserverTest.java
Change-Id: I7c488f941bf7e6ee652b784b6d41e95a48138f5a
2 files changed