Ensuring MagneticRowListeners are cleared after each test.

For tests, we use a delegate that allows to test the cancelling calls of
real animators. We also add a cleanup @After method to make sure all
listeners are cleared (by calling MagneticRowManager#reset).

Test: MagneticRowManagerImplTest
Flag: com.android.systemui.magnetic_notification_swipes
Bug: 395364166
Change-Id: I3ed647b6d6848bea22b604624d8f56932b8e7de0