Fix minimalism feature not responding to settings change

Fix the bug when we change the secure settings value through settings
app or command line, the minimalism feature does not respond to the
setting change.

Fix: 377546277
Bug: 354047572
Flag: com.android.server.notification.notification_minimalism
Test: adb shell settings secure put lock_screen_notification_minimalism
 \<1|0>
Change-Id: I6d46c7a069c3f3ce5aa0e01723df177d8225aa7b