Lockscreen bouncer: Always set INPUT_FEATURE_SENSITIVE_FOR_TRACING

The bouncer should always be treated as a sensitve window so that
interactions do now show up in the input trace, regardless of when
FLAG_SECURE is set. It should not be a sensitive window when the bouncer
is not showing.

Flag: None
Bug: 210460522
Test: manual
Test: atest NotificationShadeWindowControllerImplTest
Change-Id: I43555af2a0282d07ad01d08a0ab03a688ad3f836