Tweak popup animation

- Decrease duration
- Add alpha fade in and out
- Remove arrow scale when closing, so that
  the reversal happens immediately

These changes help the popup feel snappier while also reducing
visual jank when moving icons (as the animation accelerates in
later and the alpha stays close to 0).

Bug: 62738635
Change-Id: Ic8af4e0e5bc00913ea713853997069e8b9c8f953