Fix volume dialog dismiss animation

The root cause of the problem is that within `mController.notifyVisible(false)` `updateActiveStreamW(-1)` is called. This causes the slider to be set to inactive which changes its color. By calling the callback after the animation ended, this problem is fixed.

Bug: 240682583
Test: atest VolumeDialogImplTest, Manual, i.e. changing the volume and observing the animation when the VolumeDialog dismisses.
Change-Id: I928564202036ce7447d0cbae98302af8bf66c600