Hide keyguard status bar until end of OCCLUDED transition

While occluded, the default status bar will be visible until the
end of the transition back to LOCKSCREEN. Hide the keyguard status
bar until the end, and reset with a value of -1

Fixes: 409316487
Test: atest OccludedToLockscreenTransitionViewModelTest
Flag: EXEMPT bugfix
Change-Id: I460e9465c8a18a80becf9d8cd7430a4f62d06694