Make Notification long clickable

Notification aka ExpandableNotificationRow handle long click but it was not marked as long clickable. That confused test and that would have a possible impact on accessibility.
We implemented unit test which checks whether the notification is long clickable or not to verify the behavior and fixed the issue by marking Notification long clickable.

Test: atest PlatformScenarioTests:android.platform.test.scenario.sysui.notification.NotificationGuts#testExpandAndCollapseGuts

Bug: b/264948201
Change-Id: I34248b9e207c93c6e987f70603e8b3725c7c1ab1