Suppress battery saver suggestion notification

When users turn on battery saver manually more than 3 times, the "Tap to
schedule Battery Saver" notification will suggest users to enable
scheduling battery saver. But this notification is still shown if users
have already turned on scheduling battery saver, which is caused by no
mechanism to suppress this notification.

Solution:
Adding a mechanism to suppress battery saver suggestion if users
scheduled battery saver.

Bug: 147862112
Test: robotests
Change-Id: I8290d76dac09104e64fb98b8a9f4d783a8177d7c