Adapted the shade closing interpolator

The current interpolator wasn't working well
and was accelerating too much in certain cases.
We now finetuned those animations.

The animation has a slight acceleration to it for
slow swipes.

Test: close / open panel
Bug: 33652632
Fixes: 33652505
Change-Id: I62aa349b128dee9872b50b2af0ef419755ef7127