Fix double tapping notifications on lock screen.

http://ag/10273995 broke double tapping on notifications. This cl
restores the behavior by replacing a call to
ActivatableNotificationView#performClick with
ExpandableOutlineView#performClick.

That is to say, we needed to call the super method, as we did before
the breaking cl was checked in.

Bug: 149744457
Test: atest SystemUITests
Change-Id: Ie77ade20f74b04eb0edbe0f1806938523068175a