KeyguardBouncer#isShowing fix

KeyguardBouncer.isShowing should not return
true when the view is hidden.

Change-Id: I111aab356f6fc2367816b2ac132c0c4b140864c3
Fixes: 74583436
Fixes: 76151115
Test: packages/SystemUI/tests/src/com/android/systemui/statusbar/phone/KeyguardBouncerTest.java
Test: Swipe up on lock screen
Test: Unlock with fp from AOD, keyguard or bouncer
Test: Unlock from occluded bouncer