[flexiglass] Log when visibility changes were rejected

It's helpful for debugging to see when visibility changes for the scene
container were rejected because the visibility already had the new
value.

Bug: 416718983
Bug: 416718898
Test: manually verified that logcat displays visibility rejections now
Flag: com.android.systemui.scene_container
Change-Id: Ibf885a116590ce71d9b164fda259a8265dbeb1e7