Revert "Add new ExpandableNotificationRowController."

Revert submission 10162577-b147245740-activitable-notif-view-component

Reason for revert: Broken test. http://b/149099968
Reverted Changes:
I153797743: Add new ExpandableNotificationRowController.
If72c1e19a: Fill in ActivatableNotificationViewController.

Change-Id: Ia4b8633134841d5d3398b4d0def38c71ac9eac75