Center navbar pulse animation.

Rather than rising up slightly, it will now expand centered on
the original bar.

X was also slightly off-center due to not accounting for the view
already being centered on the screen separately.

Before: https://screenshot.googleplex.com/A2kRfEcFWzJ8jTr.png
After: https://screenshot.googleplex.com/Bj8Mf8dwZsbr9BC.png

Fix: 309611779
Test: Manual
Flag: LEGACY ANIMATE_LPNH TEAMFOOD
Change-Id: I08dac5fea111c893d2a467fbb4d6d713dc397457