[DO NOT MERGE] Update window with FLAG_SECURE when bouncer is showing

This will prevent bouncer interactions from showing up in
screenrecords or screenshots.

Fixes: 215005011
Test: atest StatusBarWindowControllerTest && take screenshot
with bouncer up

Merged-In: I3f59df865dc2dd13d4b9ac54bb2dacb7b23f0aa1
Change-Id: I8df2258863b8cede5ba112331e0446f534267ba2