Remove ImeTracker onHidden in DisplayImeController

Without the refactor, the IME leash was not reset, so effectively the hide request finished at the end of the animation. This changed, as we now report the requested visibilty and the hide request finishes later. Therefore, remove the onHidden in onAnimationEnd.

Bug: 353463205
Change-Id: I2814a9ac7764df3acb33ad015134003ec78a0688
Flag: android.view.inputmethod.refactor_insets_controller
Test: None logs only