Sync split dismiss anim scrim fadee timing with taskbar to home anim duration

* We sync the scrim fade with the taskbar animation duration
to avoid any flickers fortaskbar icons disappearing before hotseat
icons show up.
* Layer wise taskbarIcons > scrim > hotseat
as taskbarIcons are translating into place, the frame where they fade out
the scrim should also fade out so they get seamlessly replaced by hotseat icons
* In our case the scrim was staying on too long so the scrim would show before
the hotseat, making it look like a flicker.
* Now we fade away the scrim sooner

Bug: 318747712
Test: Flicker no longer occurs
Flag: None
Change-Id: I779af1826ee55bfcbced3e972f14f5f299e9aaeb