Make green SC notifications auto-cancellable.

This is a UX requirement, since user doesn't really need to act on green
"tips", it doesn't make sense that the notification stays open once the
user taps it.

Test: atest SafetyCenterNotificationTest
Bug: 291051246
Relnote: N/A
Change-Id: I809ec6c5b8b4f050775a88169f5de046ab2e1d7c