Do not hide nav bar on the homescreen from setup

FLAG_STASHED_SMALL_SCREEN is not updated after setup UI finishes.

Fixes: 337738795
Test: Finish setup, swipe home in folded, and observe home handle is visible.
Change-Id: I297e3b44f49f94ab5a1b9fe5ff16ff64c6cf2c0a
(cherry picked from commit ee67a48d)