Compute visibilities when finishing show-when-lock activity

The activity visibilities was not updated in KeyguardController
while a show-when-locked activity was finished. Therefore, the
general activity below was resumed for a short time and flickering
the screen with transition animation.

Bug: 149837574
Test: start emergency dialer and exit
Test: atest ActivityRecordTests
Change-Id: I7cea9d3e00a856c392728c7a8c825d4633b73f55