Override KeyguardStatusBarView alpha to 0 when bouncer is showing

This was not required because NPVC was applying a view level blur whenever bouncer was opened and status bar was blurred out enough to not seem visible, with ag/33333408 this doesn't happen anymore and status bar needs to be hidden explicitly

Bug: 414883107
Flag: com.android.systemui.bouncer_ui_revamp
Test: verified manually
Change-Id: I919e17af4209a4d250113de91cbac41dc51d2b53