Fix a couple of issues with app close

- Make sure to use center pivot point
- Use correct curve for alpha
- No need for the layer hack anymore because framework issue
was fixed.
- End X should be 480dp for a 411dp device, so we need to scale
it with 1.16

Test: Close app
Change-Id: Ib4587e324aeeb11921de87da7c389b2e148dc913
Fixes: 72691044